7k forces and their effects - pearson schools and fe ... · pdf filethis unit revises the...

Exploring Science edition © Pearson Education Limited 2008262

This unit revises the concepts of forces and their effects and extends pupils’ knowledge of friction, gravity and speed. These ideas are presented using a theme of outdoor sports, such as climbing and kayaking, to link to ideas about forces, friction and fl oating.

We recommend approximately 8 hours of teaching time for this unit.

From KS2 most pupils will:• know about different kinds of forces, including magnetism, gravity,

upthrust and friction• know that unbalanced forces can change the speed or direction

of movement of an object, and that forces are balanced when an object is at rest

• know that objects in water experience an upthrust, and that weight is a force measured in newtons

• be able to measure a force using a force meter• know some of the factors that increase friction between solid

surfaces and increase air resistance and water resistance.

This unit builds on ideas introduced in the QCA Scheme of Work for KS2: Unit 4E Friction and Unit 6E Balanced and unbalanced forces.

• Topic 7Ka introduces the outdoor activity theme for the unit, and revisits ideas about forces fi rst met at KS2: that forces are pushes or pulls, that forces can change the speed or direction of movement of something or change its shape. This topic also looks at the difference between mass and weight. Could level work looks at bathroom scales.

• Topic 7Kb looks at friction, the effects of surface roughness on friction, and lubrication. It also discusses various ways in which friction is helpful and not helpful. Could level work asks pupils to analyse the results of a weight and friction experiment. The practical activity on investigating the factors affecting friction can be used for training or assessment for Attainment Target 1, and a set of level descriptions is provided in the ASP.

• Topic 7Kc looks at fl oating and sinking, and emphasises that things fl oat when weight is balanced by upthrust. Could level work is provided on the Plimsoll line and Archimedes, and in looking in more detail at how the use of friction and buoyancy can help to keep outdoor sports safe.

• Topic 7Kd looks at balanced forces, and how forces are measured using springs. Could level work is provided on climbing ropes.

• Topic 7Ke introduces the idea that different units for speed can be appropriate for different circumstances. Vehicle stopping distances and distance–time graphs are introduced. Could level work is provided on speed records.

ExpectationsKey concepts At the end of this unit…

All pupils must:(L4) Recognise some pieces of equipment that make use of forces. (L5) Recognise that ideas about forces have changed as scientists have carried out more experiments.

Most pupils should:(L6) Describe examples of how using equipment to control forces lets us do things that we would not be able to do. (L6) Explain why safety standards are needed for sporting equipment.

Some pupils could: (L7) Recall examples of how and why ideas about forces have changed.

Key processes At the end of this unit…

All pupils must:(L4) Use force meters to measure forces accurately using the correct units. (L4) Make and test predictions.

Most pupils should:(L5) Make predictions that are explained using scientifi c knowledge.(L6) Use ideas about the causes of friction to suggest one or more variables that may affect the amount of friction. (L6) Plan to control variables in an investigation, explaining why they need to be controlled. (L6) Make careful observations and repeat them where necessary. (L6) Draw conclusions and match them to predictions.

Some pupils could:(L7) Use secondary sources to identify a range of variables that may affect the amount of friction, and plan an investigation to investigate them. (L7) Present data as a line graph with a line of best fi t.

Range and contentAt the end of this unit…

All pupils must:(W4) Recall that a force is a push or a pull. (L4) Name and identify some different forces. (L4) Identify contact and non-contact forces. (L5) Describe what friction, upthrust and gravity do. (L5) Identify the different sorts of friction and say how they can be useful or not.

Most pupils should:(L5) Describe how forces acting on an object can work with or against each other. (L6) Draw diagrams to show the directions in which forces act and their sizes. (L6) Identify balanced and unbalanced forces.(L6) Explain how friction can be reduced. (L6) Describe the difference between mass and weight. (L7) Explain what is meant by speed and be able to calculate speeds. (L7) Explain what is meant by density and be able to calculate densities.

Some pupils could: (L7) Explain why weights change when objects are taken to other planets. (L7) Recall what a resultant force is and calculate resultant forces.

For a list of updated and vetted websites that can be used to support your teaching of this unit please visit theExploring Science: How Science Works E-Forum(http://groups.google.co.uk/group/exploringscience).

7K Forces and their effects

7K

UNIT12.indd 262 12/3/08 15:07:31

© Pearson Education Limited 2008 263Exploring Science edition

7K NC Statements coveredFrom KS2

Statement TopicSc4 2a (pt)

About ... forces of attraction between magnets and magnetic materials.

7Ka

Sc4 2b That objects are pulled downwards because of the gravitational attraction between them and the Earth.

7Ka, 7Kc, 7Kd

Sc4 2c About friction, including air resistance, as a force that slows moving objects and may prevent objects from starting to move.

7Ka, 7Kb

Sc4 2e How to measure forces and identify the direction in which they act.

7Ka, 7Kb, 7Kc, 7Kd

At KS31 Key concepts

Statement Topic1a Using scientifi c ideas and models to explain

phenomena and developing them to generate and test theories.

7Kb, 7Kc, 7Kd

1b Critically analysing and evaluating evidence from observations and experiments.

7Ka, 7Kb, 7Kc, 7Kd

2a Exploring how the creative application of scientifi c ideas can bring about technological developments and consequent changes in the way people think and behave.

all

2b Examining the ethical and moral implications of using and applying science.

7Kc, 7Ke

3a Recognising that modern science has its roots in many different societies and cultures and draws on a variety of valid approaches to scientifi c practice.

7Ka, 7Kc, 7Kd

2 Key processes

Statement Topic1a Use a range of scientifi c methods and

techniques to develop and test ideas and explanations.

All

1b Assess risk and work safely in the laboratory fi eld and workplace.

7Kb, 7Kc, 7Kd, 7Ke

1c Plan and carry out practical and investigative activities, both individually and in groups.

7Ka, 7Kb, 7Kc, 7Kd

2a Obtain, record and analyse data from a wide range of primary and secondary sources, including ICT sources and use their fi nding to provide evidence for scientifi c explanations.

all

2b Evaluate scientifi c evidence and working methods.

7Kb, 7Kd

3a Use appropriate methods, including ICT, to communicate scientifi c information and contribute to presentations and discussions about scientifi c issues.

7Kb, 7Kd, 7Ke

3 Range and content

Statement Topic1b Forces are interactions between objects and

can affect their shape and motion.all

4 Curriculum opportunities

Statement Topica Research, experiment, discuss and develop

arguments.7Kb, 7Kc, 7Kd

b Pursue an independent enquiry into an aspect of science of personal interest.

7Kb, 7Kc, 7Kd

c Use real-life examples as a basis for fi nding out about science.

all

e Experience science outside the school environment including in the workplace, where possible.

7Ka, 7Kc

h Explore contemporary and historical scientifi c developments and how they have been communicated.

7Ka, 7Kc, 7Kd

j Consider how knowledge and understanding of science informs personal and collective decisions, including those on substance abuse and sexual health.

7Ka, 7Kc

k Make links between science and other subjects and areas of the curriculum.

7Ka, 7Kb, 7Kc

Links with other units

9J Mass and weight. 9L Pressure and moments.9K Speed calculations.

Cross-curricular links

Topic Links7Ke PSHEE – Road safety.

Skills opportunities for Personal, Learning and Thinking Skills (PLTS), literacy, numeracy and ICT are included in the individual topic notes.

Forces and their effects 7K

7K

UNIT12.indd 263 12/3/08 15:07:32


Framework statements covered by Unit 7K

1 How Science Works

1.1 Explanations, arguments and decisions

Code Framework threads Year 7 Topic1.1a3 Scientifi c thinking: developing argument Identify a range of scientifi c data and other evidence to

back an argument and the counterclaim in less complex and/or familiar contexts, e.g. establishing a wind farm.

7Ka, 7Kc, 7Kd

Recognise that scientifi c evidence can be used to support or disprove theories.

7Ka

1.1b Applications, implications and cultural understanding Describe some benefi ts and drawbacks of scientifi c developments with which they are familiar.

7Ka, 7Kb, 7Kc7Kd, 7Ke

Recognise that decisions about the use and application of science and technology are infl uenced by society and individuals.

7Ka, 7Kb, 7Ke

1.1c Communication for audience and with purpose Use key scientifi c vocabulary and terminology in discussions and written work.

7Kb, 7Ke

Identify and use the conventions of various genres for different audiences and purposes in scientifi c writing.

7Kb, 7Ke

1.2 Practical and enquiry skills

Code Framework threads Year 7 Topic1.2a Using investigative approaches: planning an approach Describe an appropriate approach to answer a scientifi c

question using a limited range of information and making relevant observations or measurements.

7Kb, 7Kc, 7Kd

1.2b Using investigative approaches: selecting and managing variables

Recognise the range of variables involved in an investigation and decide which to control.

7Kb, 7Kc

1.2c Using investigative approaches: assessing risk and working safely

Explain how action has been taken to control obvious risk and how methods are adequate for the task.

7Kb, 7Kc, 7Kd

1.2d Using investigative approaches: obtaining and presenting primary evidence

Describe and record observations and evidence systematically.

7Ka, 7Kb, 7Kc7Kd

Recognise that the presentation of experimental results through the routine use of tables, bar charts and simple graphs makes it easier to see patterns and trends.

7Ka, 7Kb, 7Kd

1.2e Working critically with primary evidence Describe patterns and trends in results and link this evidence to any prediction made.

7Ka, 7Kb, 7Kc7Kd

Describe and suggest how planning and implementation could be improved

7Kb, 7Kc, 7Kd

1.2f Working critically with secondary evidence Describe patterns and trends in secondary evidence and link these to the prediction or conclusion drawn.

7Kb, 7Kd, 7Ke

4 Energy, electricity and forces

Code Framework sub-strands Year 7 Topic4.2 Forces Recognise the forces acting on an object in different

situations..7Ka, 7Kc, 7Kd7Ke

Distinguish between situations involving balanced and unbalanced forces.

7Ka, 7Kc, 7Kd7Ke

Recognise that forces can combine or wholly or partly cancel each other out and their size and direction can be represented using arrows.

7Ka, 7Kd, 7Ke

Recognise that there are contact forces and forces that act at a distance

7Ka, 7Kb, 7Kd7Ke


7K

UNIT12.indd 264 12/3/08 15:07:32


7K R

oute

s th

rou

gh t

he

un

itTh

is p

age

sugg

ests

rou

tes

thro

ugh

the

Uni

t at t

hree

diff

eren

t lev

els,

usi

ng s

ome

of th

e ta

sks

prov

ided

. Man

y ot

her

teac

hing

seq

uenc

es a

re p

ossi

ble

usin

g th

e al

tern

ativ

e te

achi

ng m

ater

ials

and

tas

ks p

rovi

ded

or

by a

ddin

g yo

ur o

wn

mat

eria

ls. W

e re

com

men

d ap

prox

imat

ely

8 ho

urs

of te

achi

ng ti

me

for

this

uni

t.

Top

icLe

vel

Lear

nin

g ob

ject

ives

Key

wor

ds

Task

s7K

aM

ust

All

pupi

ls m

ust:

desc

ribe

wha

t a fo

rce

is a

nd d

escr

ibe

cont

act a

nd n

on-c

onta

ct fo

rces

; exp

lain

that

fo

rces

cha

nge

the

shap

e, s

peed

and

dire

ctio

n of

an

obje

ct; e

xpla

in h

ow a

forc

e ca

n be

mea

sure

d, a

nd

reca

ll th

e un

its; a

ppre

ciat

e th

at m

ass

and

wei

ght a

re d

iffer

ent t

hing

s, a

nd r

ecal

l the

uni

ts fo

r bo

th;

reca

ll th

at id

eas

abou

t for

ces

have

cha

nged

ove

r tim

e.

air

resi

stan

ce, c

onta

ct fo

rce,

forc

e,

forc

e m

eter

, fric

tion,

gra

m (

g), g

ravi

ty,

kilo

gram

(kg

), m

ass,

new

ton

(N),

ne

wto

n m

eter

, non

-con

tact

forc

e,

upth

rust

, wat

er r

esis

tanc

e, w

eigh

t

Star

ter

1, S

tart

er 5

, Exp

lorin

g 1,

Exp

lorin

g 2,

Ex

plai

ning

2, P

lena

ry 1

, Ple

nary

2, H

omew

ork

1

Shou

ldM

ost p

upils

sho

uld:

rec

all t

hat t

he s

ize

of a

forc

e ca

n be

rep

rese

nted

by

the

size

of a

n ar

row

on

a di

agra

m; e

xpla

in th

e di

ffere

nce

betw

een

mas

s an

d w

eigh

t.m

agne

tism

, sta

tic e

lect

ricity

Star

ter

2, S

tart

er 5

, Exp

lorin

g 1,

Exp

lorin

g 3,

Ex

plai

ning

1, E

xpla

inin

g 2,

Ple

nary

1, P

lena

ry 2

, H

omew

ork

2C

ould

Som

e pu

pils

cou

ld: e

xpla

in w

hy th

e w

eigh

t of a

n ob

ject

wou

ld c

hang

e if

take

n to

the

Moo

n; e

xpla

in

how

bat

hroo

m s

cale

s w

ork.

Star

ter

2, S

tart

er 3

, Sta

rter

5, E

xplo

ring

3,

Expl

aini

ng 1

, Exp

lain

ing

2, E

xpla

inin

g 3,

Pl

enar

y 1,

Ple

nary

2, H

omew

ork

37K

bM

ust

All

pupi

ls m

ust:

expl

ain

that

fric

tion

is a

forc

e be

twee

n tw

o su

rfac

es to

uchi

ng e

ach

othe

r; ex

plai

n th

at

fric

tion

slow

s th

ings

dow

n; r

ecal

l tha

t rou

gh s

urfa

ces

prod

uce

mor

e fr

ictio

n th

an s

moo

th s

urfa

ces;

de

scrib

e so

me

situ

atio

ns in

whi

ch fr

ictio

n is

hel

pful

and

som

e w

here

it is

not

; rec

all t

hat a

ir re

sist

ance

an

d w

ater

res

ista

nce

are

form

s of

fric

tion.

Star

ter

2, E

xpla

inin

g 1,

Exp

lain

ing

2,

Expl

aini

ng 3

, Ple

nary

2, E

xpla

inin

g 5,

Ple

nary

3

Expl

aini

ng 4

, Exp

lorin

g 1,

Ple

nary

5, H

omew

ork

1

Shou

ldM

ost p

upils

sho

uld:

des

crib

e th

e ef

fect

s of

fric

tion;

exp

lain

that

fric

tion

can

be r

educ

ed b

y ad

ding

a

lubr

ican

t; be

abl

e to

des

ign

a fa

ir te

st to

inve

stig

ate

fric

tion;

app

ly id

eas

abou

t for

ces

and

fric

tion

in

diffe

rent

con

text

s.

lubr

ican

t, lu

bric

atio

nSt

arte

r 1,

Sta

rter

2, E

xpla

inin

g 1,

Exp

lain

ing

2,

Expl

aini

ng 3

, Exp

lain

ing

5, P

lena

ry 1

Expl

aini

ng 4

, Exp

lorin

g 1,

Ple

nary

4, H

omew

ork

2C

ould

Som

e pu

pils

cou

ld: r

ecal

l tha

t mat

eria

ls s

uch

as P

TFE

prod

uce

very

litt

le fr

ictio

n an

d ar

e us

ed in

m

akin

g no

n-st

ick

pans

.St

arte

r 1,

Sta

rter

2, E

xpla

inin

g 1,

Exp

lain

ing

2,

Expl

aini

ng 3

, Exp

lain

ing

5, P

lena

ry 1

Expl

aini

ng 4

, Exp

lorin

g 1,

Ple

nary

4, H

omew

ork

27K

cM

ust

All

pupi

ls m

ust:

reca

ll th

at u

pthr

ust i

s a

forc

e th

at p

ushe

s up

in w

ater

or

air;

expl

ain

that

an

obje

ct w

ill

fl oat

whe

n th

e up

thru

st a

nd w

eigh

t are

bal

ance

d.St

arte

r 1,

Exp

lorin

g 1,

Exp

lorin

g 2,

Exp

lorin

g 4,

Ex

plai

ning

1, P

lena

ry 1

, Ple

nary

3, H

omew

ork

1Sh

ould

Mos

t pup

ils s

houl

d: r

ecal

l tha

t the

am

ount

of u

pthr

ust d

epen

ds o

n th

e liq

uid

the

obje

ct is

fl oa

ting

in;

desc

ribe

how

to m

easu

re th

e vo

lum

e of

reg

ular

and

irre

gula

r ob

ject

s; d

escr

ibe

how

to c

alcu

late

de

nsity

; exp

lain

how

to w

ork

out i

f som

ethi

ng w

ill fl

oat b

y co

mpa

ring

the

dens

ity o

f the

obj

ect a

nd th

e liq

uid;

app

ly th

eir k

now

ledg

e of

fric

tion,

forc

es a

nd fl

oatin

g to

out

door

act

iviti

es.

disp

lace

men

t, de

nsity

Star

ter

1, E

xplo

ring

2, E

xplo

ring

3, E

xpla

inin

g 1,

Ex

plai

ning

2, E

xpla

inin

g 3,

Exp

lain

ing

4,

Plen

ary

1, H

omew

ork

2

Cou

ldSo

me

pupi

ls c

ould

: rec

all t

hat A

rchi

med

es w

as th

e fi r

st p

erso

n to

exp

lain

why

obj

ects

fl oa

ted.

Star

ter

1, E

xplo

ring

2, E

xplo

ring

3, E

xpla

inin

g 1,

Ex

plai

ning

2, E

xpla

inin

g 3,

Exp

lain

ing

4,

Expl

aini

ng 5

, Ple

nary

1, H

omew

ork

37K

dM

ust

All

pupi

ls m

ust:

desc

ribe

the

diffe

renc

e be

twee

n ba

lanc

ed a

nd u

nbal

ance

d fo

rces

; des

crib

e w

hat w

ill

happ

en in

sim

ple

situ

atio

ns in

volv

ing

bala

nced

or

unba

lanc

ed fo

rces

; rec

all t

hat i

deas

abo

ut fo

rces

ha

ve c

hang

ed a

s ne

w e

xper

imen

ts h

ave

been

car

ried

out.

bala

nced

forc

es, u

nbal

ance

d fo

rces

Star

ter

1, S

tart

er 3

, Exp

lorin

g 1,

Exp

lain

ing

1,

Expl

aini

ng 2

, Ple

nary

4, H

omew

ork

1

Shou

ldM

ost p

upils

sho

uld:

des

crib

e so

me

diffe

renc

es b

etw

een

mod

ern

idea

s ab

out f

orce

s an

d ol

der

idea

s,

and

the

role

of e

xper

imen

tatio

n in

cha

ngin

g id

eas;

rec

all t

hat a

spr

ing

stre

tche

s ev

enly

up

to a

cer

tain

po

int;

desc

ribe

how

this

prin

cipl

e is

use

d in

man

y fo

rce

met

ers

(als

o kn

own

as n

ewto

n m

eter

s).

elas

tic, s

tatio

nary

Star

ter

1, E

xplo

ring

1, E

xplo

ring

2, E

xpla

inin

g 1,

Ex

plai

ning

2, P

lena

ry 1

, Hom

ewor

k 2

Cou

ldSo

me

pupi

ls c

ould

: rec

all t

hat s

prin

gs h

ave

an e

last

ic li

mit

beyo

nd w

hich

str

etch

ing

is n

on-u

nifo

rm;

expl

ain

som

e ap

plic

atio

ns o

f ela

stic

ity (

othe

r th

an fo

rce

met

ers)

.St

arte

r 1,

Exp

lorin

g 1,

Exp

lorin

g 2,

Exp

lain

ing

1,

Expl

aini

ng 2

, Ple

nary

1, H

omew

ork

37K

eM

ust

All

pupi

ls m

ust:

stat

e th

at s

peed

is h

ow fa

r an

obj

ect m

oves

dur

ing

a se

t per

iod

of ti

me;

rec

all t

hat

spee

d is

nor

mal

ly m

easu

red

in m

/s, k

m/h

or

mph

.km

/h, m

/s, m

ph, s

peed

Star

ter

1, E

xpla

inin

g 1,

Exp

lain

ing

2, E

xplo

ring

2,

Expl

aini

ng 3

, Ple

nary

4, H

omew

ork

1Sh

ould

Mos

t pup

ils s

houl

d: in

terp

ret a

sim

ple

dist

ance

–tim

e gr

aph;

exp

lain

wha

t thi

nkin

g di

stan

ces,

bra

king

di

stan

ces

and

stop

ping

dis

tanc

es a

re, a

nd h

ow th

ey a

re a

ffect

ed b

y ro

ad c

ondi

tions

and

driv

er

aler

tnes

s; s

ugge

st s

ome

reas

ons

why

saf

ety

stan

dard

s ar

e ne

eded

in c

erta

in s

ituat

ions

.

brak

ing

dist

ance

, dis

tanc

e–tim

e gr

aph,

st

oppi

ng d

ista

nce,

thi

nkin

g di

stan

ce.

Star

ter

1, E

xpla

inin

g 1,

Exp

lorin

g 1,

Exp

lain

ing

2,

Expl

aini

ng 3

, Ple

nary

4, P

lena

ry 5

, Hom

ewor

k 2

Cou

ldSo

me

pupi

ls c

ould

: app

ly id

eas

abou

t for

ces

and

times

to a

thle

tics

reco

rds.

Star

ter

1, E

xpla

inin

g 1,

Exp

lorin

g 1,

Exp

lain

ing

2,

Expl

aini

ng 3

, Ple

nary

4, P

lena

ry 5

, Hom

ewor

k 3


7K

UNIT12.indd 265 12/3/08 15:07:33


7K Background information7Ka – Sport and forces/The forces are with usThe classifi cation of forces into contact and non-contact forces helps pupils to categorise what they should already know about forces.

For the sake of simplicity the term resultant force has not been used. A resultant force is the combined effect of two or more forces acting on an object.

Isaac Newton (1642–1727), after whom the unit of force is named, was a physicist and mathematician. He published his research on the motion of bodies and the law of universal gravitation in a book called Philosophiae naturalis principia mathematica (usually known as the Principia) in 1687. He was the fi rst person to produce a mathematical explanation how gravity controlled the planets.

Weight and massIt is important to emphasise that weight is a force caused by gravity acting on our bodies (or any other object made of matter). Weight changes if the force of gravity changes. Mass (the amount of matter in an object) is always the same – it is not affected by gravity.

The weight of an object can be calculated by multiplying the mass by the local gravitational fi eld strength (approximately 10 N/kg on the surface of the Earth). If weight = mass × gravity, then an object in deep space far away from any planets or stars has no weight because gravity in space is taken as zero (but see also Background information for Topic 7Ld). On Earth, the strength of gravity gets smaller the higher you go above sea level. We would all weigh less if we took our bathroom scales to the top of Mount Everest, but we would still have the same mass.

7Kb – FrictionWhat causes friction?Even the smoothest surfaces are very uneven at the microscopic level. Electron micrograph pictures of ‘smooth’ surfaces show a number of projections above the surface. Two surfaces in contact will actually only be touching via these projections. Thus the area in contact is very small, and the pressure on the touching points very large. There is an attraction between the molecules on the different surfaces, so they tend to stick together. This adhesion is what causes friction.

Factors affecting frictionFriction is a force that always acts to oppose the relative motion of two surfaces. The size of the frictional force is proportional to the size of the force pressing the two surfaces together, and on the type of materials in contact. The size of the frictional force does not depend on the area in contact (as long as the force pressing the surfaces together is constant), nor does it depend on the speed of movement.

Smoother surfaces will have more points of contact between them, thus reducing the pressure on the projections and reducing the attraction between the molecules in contact.

Lubrication reduces friction by preventing the surfaces touching each other. Wet roads are lubricated by water, which reduces the grip of tyres. The tread on tyres is there to channel the water away from the surface, not to increase the grip because of increased roughness. Racing cars use ‘slicks’ (tyres with no tread) when the track is dry.

Simplifying frictionIt is probably best to present friction to pupils as being caused by rough surfaces ‘catching on each other’, which is an acceptable simplifi cation for Year 7 pupils. The difference between rough and smooth surfaces can be explained by the smooth surface having fewer ‘sticking out bits’ to catch on the other surface.

Air resistance and water resistance (both known as drag) are introduced in the Pupil’s Book as forms of friction. Gases and liquids are collectively referred to as fl uids, and the causes of drag in fl uids are not the same as the causes of friction between solid surfaces. A body moving through a fl uid will drag some fl uid with it, causing the fl uid near the body to move at different speeds. Drag is also caused by changes in fl uid pressure and fl ow pattern around the body. Drag in fl uids depends on the density and viscosity of the fl uid, on the shape and size of the body, and on the speed of movement (varying with the square of the speed). The difference in density between water and air explains why water resistance is much more noticeable than air resistance.

7Kc – That fl oating feeling/Focus on Safe sportsThe upthrust on an object is equal to the weight of water being displaced (pushed aside) by that object. The more water displaced, the greater the upthrust. Salt water is denser than pure water, so the mass (and therefore weight) of water an object displaces is greater if it is salt water, and the upthrust is also greater. Some pupils may have noticed that they fl oat better in the sea than in the swimming pool. The opposite effect occurs in warm or hot water – this is less dense than cooler water, so a smaller weight of water is displaced and the upthrust is less. This is the principle behind the Plimsoll line. A ship loaded in cold, dense water will fl oat lower down when it enters warm tropical waters. It sinks lower because it displaces a bigger volume of the less dense tropical water. The Plimsoll line indicates safe loading levels for ships according to the type of water they are in: fresh water, tropical water, north Atlantic sea (i.e. salty and cold) etc.

A ‘rule’ for determining if something will fl oat is that an object will fl oat in a liquid if it is less dense than that liquid. In the case of steel ships, steel itself will not fl oat but, because of the air spaces within the ship, the average density of the whole ship is less than that of water.

Archimedes (287–212 BCE) was a Greek mathematician. He was the fi rst person to understand what made an object fl oat and wrote the law called Archimedes’ Principle. It is said that he shouted ‘Eureka!’ (‘I have found it!’) when he climbed into his bath and noticed the water level rising. When the Romans captured his home town on the island of Sicily, a Roman soldier told him to follow him to see the Roman governor. Archimedes asked the soldier to wait. The soldier was so incensed by this request that he killed him.

A Galileo thermometer works because water expands when heated, and so its density also changes. The glass containers inside the thermometer are made to have different densities, and fl oat to the surface at different temperatures.

7Kd – Balancing actBalanced forces and action–reaction pairsA detailed study of forces would make the distinction between balanced forces and action–reaction pairs (as described by Newton’s third law of motion). Action–reaction pairs are always equal in magnitude and in opposite directions, are of the same type, and act on different bodies. To take one example from the Pupil’s Book:

This is the simple version presented in the book, showing balanced forces on the boat.


7K

UNIT12.indd 266 12/3/08 15:07:34


If the action–reaction pairs are considered, the picture becomes more like this (not all of the vertical forces have been shown, for clarity):

As far as possible, the examples given in this unit avoid showing action–reaction pairs because the lack of distinction between balanced forces and action–reaction pairs is considered an acceptable simplifi cation at this level.

Measuring forcesThe main instrument used by pupils is the force meter, also called a newton meter. The term ‘spring balance’ is sometimes used, but in science ‘balance’ usually refers to an instrument for determining mass, not weight. The principle behind all force measuring instruments is the measurement of the change of shape brought about by an applied force.

Elastic and plasticMaterials or objects (such as springs) which stretch when a force is applied and then return to their original shape/dimensions are called elastic. Materials that are not elastic are plastic – when a force is applied they deform but do not return to their original shape when the force is removed.

Elastic limit and Hooke’s LawMaterials and springs are elastic only up to a certain point. If suffi cient force is applied the deformation will be permanent – the material has exceeded its elastic limit. Below this limit the stretching is caused by atoms in the material moving further away from each other; when the force is removed the atoms resume their normal positions. There is a linear relationship between the load and the extension, as stated in Hooke’s Law, ‘the extension is directly proportional to the load’. In other words doubling the load will double the extension. Beyond the elastic limit the force causes planes of atoms to move over each other – to change position – and the material is permanently deformed.

Stretching polymersIt is important to use springs in stretching experiments if pupils are to discover a proportional relationship. Rubber or elastic bands do not stretch in a uniform manner – the initial force causes coiled or ‘zig-zag’ molecules to straighten out (which happens relatively easily); when most molecules have been straightened, the distances between the atoms are affected and the material

becomes much more diffi cult to stretch.

7Ke – The need for speed/Safety standardsPupils tend to grasp the basic concept of speed fairly easily. The main problem is likely to be how the various units (m/s, km/h, mph) relate to each other. Pupils will be familiar with mph but should be encouraged to look at speed in terms of m/s and km/h.

The stopping distances quoted in the Highway Code were measured some time ago. The distances will be increased by factors such as wet or icy roads, tired or inebriated drivers. Modern cars, particularly sports models, could have stopping distances shorter than those quoted.

For reference purposes, a few ‘speed records’ are shown below:

• The fastest land animal is the cheetah at 113 km/h (70 mph).• The slowest growing animal is a variety of the deep sea clam

which grows only 8 mm in 100 years.• In 1994, in the USA, someone ‘ran’ 50 m on their hands in just

under 17 s.• The fastest growing plant is bamboo, at 90 cm per day.

The fastest human has not been quoted, as this changes as records are broken.


7K

UNIT12.indd 267 12/3/08 15:07:34


7Ka

Pupil’s materials

Number and title Level Location Type Tasks

Sport and forces Must/Should PB p149 Classwork Starter 5

The forces are with us Must/Should PB p150–151 Classwork Explaining 2

7K Quick Quiz Must/Should ASP Classwork Starter 4

7K Quick Quiz Answer Sheet Must/Should ASP Classwork Starter 4

7Ka Quick Check Must/Should ASP Classwork Plenary 1

7Ka Word Sheet Must/Should ASP Homework

7Ka(1) The forces are with us Must CHAP Access Explaining 2

7Ka(2) Forces in action Must/Should CHAP Practical Exploring 1

7Ka(3) Ideas about forces Must/Should CHAP Classwork Exploring 4

7Ka(4) Find the forces Must CHAP Homework Homework 1

7Ka(5) Forces reverseword Should CHAP Homework Homework 2

7Ka(6) Bathroom scales Could CHAP Homework Homework 3

SS1–4 Thinking Skills Should CHAP Skills Sheet Plenary 4

ObjectivesAll pupils must:

(1) describe what a force is and describe contact and non-contact forces

(2) explain that forces change the shape, speed and direction of an object

(3) explain how a force can be measured, and recall the units(4) appreciate that mass and weight are different things, and

recall the units for both(5) recall that ideas about forces have changed over time.

Correctly use the words air resistance, contact force, force, force meter, friction, gram (g), gravity, kilogram (kg), mass, newton (N), newton meter, non-contact force, upthrust, water resistance, weight.

Most pupils should:(6) recall that the size of a force can be represented by the size

of an arrow on a diagram(7) explain the difference between mass and weight.

Correctly use the words magnetism, static electricity.Some pupils could:

(8) explain why the weight of an object would change if taken to the Moon

(9) explain how bathroom scales work.

Topic notes• Targets for the lesson can be accessed via the ActiveBook or

ActiveTeach from the link next to the initiator question.• Misconception: many pupils will think that mass and weight are

the same thing.

Be prepared: 7KaExplaining 1: ice cubes.

Exemplar topic plans

MUST

PB pages 149–151

Starter 1Starter 5Exploring 1Exploring 2Explaining 2Plenary 1Plenary 2Homework 1

SHOULD

PB pages 149–151

Starter 2Starter 5Exploring 1Exploring 3Explaining 1Explaining 2Plenary 1Plenary 2Homework 2

COULD

PB pages 149–151

Starter 2Starter 3Starter 5Exploring 3Explaining 1Explaining 2Explaining 3Plenary 1Plenary 2Homework 3

SHOULD 2 Yr KS3*

PB pages 149–153

7Ka Starter 27Ka Starter 57Ka Exploring 37Ka Explaining 27Kb Plenary 27Kb Explaining 27Kb Explaining 57Kb Plenary 1

7Kb Starter 17Kb Explaining 47Kb Exploring 17Kb Plenary 47Kb Homework 3

* This table is repeated in 7Kb.

7Ka Sport and forces

UNIT12.indd 268 12/3/08 15:07:35


7Ka

Starters

1: Forces revisionAfl As the fi rst part of the topic is largely KS2 revision, start

by asking pupils to write down the key facts they recall about forces. Then elicit ideas from the class about the different kinds of forces and what they can do. Ask for ideas about how forces are measured – many pupils will have come across force meters at KS2. Remind them of the units. Ask pupils to revisit their lists and add anything they missed.

2: Forces concept mapAfl Ask pupils to draw a concept map to show what they know

about forces. If necessary, give them a list of words to include, such as push, pull, spring, force, magnet etc. This task can act as a baseline assessment to help you to plan the teaching for the rest of the unit.

3: Ideas about forces ATThe third AT presentation link on page 150 opens Ideas about forces – a concept cartoon with different statements about forces, some of which are incorrect. Ask pupils to comment on each statement, saying if they think it is correct or not, and if not, why not. Keep answers to revisit at the end of the unit. Some of the statements apply to fl oating and to friction, which are covered in later topics.

4: Quick QuizAfl Use the 7K Quick Quiz as a baseline assessment for this unit.

Pupils could record their answers on the 7K Quick Quiz Answer Sheet.

5: Pupil’s Book page 149 (AT)This reminds pupils of some of the forces they should have studied at KS2, introduces the outdoor sport theme for the unit and also the

idea that many modern sports would not be possible without technological developments (such as the aircraft needed for skydiving).

The AT video link on page 149 opens Outdoor sports – a clip showing Jim, an instructor at an outdoor centre talking about the kinds of sports taught at the centre, and in general terms about how some technological developments have made climbing safer.

Exploring tasks

1: Practical: Circus of forcesPlace equipment around the lab, numbered to match Worksheet 7Ka(2).

1 A pair of magnets.2 An ice cube and a similar sized block of wood, for pupils to push

along the bench.3 A piece of natural string (the rougher the better) and a piece of

plastic string, for pupils to tie knots with.4 A spring that can be stretched between the hands without

exceeding its elastic limit. Pupils should be able to feel that the force exerted by the spring increases as the extension increases.

5 A force meter and an object to weigh.6 Observing the time taken for a piece of paper to fall varying with

the amount it is crumpled up.

Clear up any water spills from melting ice.

Resources (per group)(1 to 3 sets only if done as a circus, depending on class size):1 2 bar magnets (N and S marked); 2 ice cube; similar sized block of wood; 3 piece of natural string; piece of plastic string; 4 spring; 5 force meter; object to weigh that can be hooked onto force meter; 6 sheets of paper; Worksheet 7Ka(2).

Topic task plannerUse these tasks to adapt the exemplar topic plans to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’). AT or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use.

Task Level NC Type Objectives Skills 1 KC 2 KP 3 RC 4 CO

Starter 1 M/S 4 Classwork 1, 2, 3 PLTS (Ep, Rl) 1b

Starter 2 S 4–5 Classwork 1–4, 6 PLTS (Ct) 1b

Starter 3 M/S 4–5 Classwork 2 PLTS (Ep) 1b

Starter 4 M/S 4–5 Classwork all topics PLTS (Rl) 1b

Starter 5 M/S 4 Classwork 1, 2 2a 1b c, e, j, k

Exploring 1 M/S 4 Practical 1-3 PLTS (Tw) 1a, 1c, 2a

1b

Exploring 2 M 4 Practical 3 PLTS (Tw), Num (M) 1a, 1c, 2a 1b

Exploring 3 M/S 5–6 Practical 3, 4, 7 PLTS (Tw), Num (M, L) 1b 1a, 1c, 2a 1b

Exploring 4 M/S 4–5 Classwork 5 3a 1b h

Explaining 1 M/S 5–6 Classwork 4, 7 PLTS (Ct) 1b

Explaining 2 M/S 4–6 Classwork 1, 3, 4, 6, 7 1b c

Explaining 3 C 5–6 Classwork 9 2a 1b c

Plenary 1 M/S 4–5 Classwork 1, 6 PLTS (Ep, Rl), Lit (WF) 1b

Plenary 2 M/S 4 Classwork 1, 6 1b c

Plenary 3 M 4 Classwork 1 1b

Plenary 4 S 4 Classwork 1 PLTS (Ct) 1b

Plenary 5 M 4–5 Classwork 1, 4, 7 Lit (WF) 1b

Homework 1 M 4 Homework 1 Lit (WF) 1b

Homework 2 S 4 Homework 1, 3, 4, 7 Lit (WF) 1b

Homework 3 C 5–6 Homework 9 Lit (EC) 1b c

Sport and forces 7Ka

UNIT12.indd 269 12/3/08 15:07:36


7Ka

2: Practical: More forcesGive pupils practice using force meters by asking them to weigh a range of objects, and also to measure other forces, such as the force required to open a door, to drag a book or other object along a bench, or the force they can exert with their little fi ngers.

Resources (per group)Force meter; variety of objects to weigh and/or pull.

3: Practical: Mass and weightThis practical is best carried out after Explaining 1. Ask pupils to weigh a range of objects using scales marked in both grams/kilograms and newtons. If such scales are not available, provide a range of labelled masses (slotted masses will do, but other objects could be used if their masses are measured before the lesson and marked on them). If possible, use bathroom scales to fi nd the masses of the pupils themselves. Be aware that some pupils may be sensitive about their weight/mass. Ask pupils to compile a table of weight against mass. Pupils could be asked to plot graphs to show their results, and work out the weight of 1 g. Pupils can then use their graphs to work out the weight of other items of known mass.

Resources (per group)Access to a range of items with masses marked; force meter; bathroom scales; graph paper.

4: Aristotle’s ideas about forcesWorksheet 7Ka(3) introduces Aristotle’s ideas about why things fall, fl oat or rise, and contrasts them with our current ideas.

Explaining tasks

1: Mass and weightElicit pupils’ ideas about mass and weight by asking them how much they weigh – answers are likely to be in kilograms or stones. You could then ask what happens to their weight if they go into space, but point out that their bodies would not have changed. This introduces the need for another measurement (mass) to quantify the amount of substance in something. Discuss the fact that the scientifi c defi nition of weight is the force caused by gravity acting on our bodies and, because it is a force, its units are in newtons. It is acceptable to talk about weighing 5 kg of potatoes in a supermarket, but not in a science lesson!

2: Pupil’s Book pages 150–151This introduces the idea of contact and non-contact forces, and discusses the difference between mass and weight.

• Must: read through the text with pupils and discuss the questions with them. Rather than having pupils write answers to the questions, they could just go straight to the cloze exercise provided (see Plenary 5).

Worksheet 7Ka(1) is the Access Sheet.

3: Practical: Bathroom scalesRemove the cover from a set of bathroom or kitchen scales (mechanical, not electronic) to fi nd out how they work – there is usually a metal bar that deforms when someone stands on it, and a mechanism to transform the deformation into movement of the dial.

ResourcesSet of mechanical bathroom or kitchen scales.

Plenaries

1: Quick CheckAfl Use the Quick Check as a plenary activity, asking pupils (or

groups of pupils) to add arrows to the diagrams, and then discuss the sizes of the forces. The discussion could also include the names of the forces involved, to help to reinforce the scientifi c vocabulary used in the lesson.

2: Where are the forces? ATAfl The AT animation link on page 150 opens Where are the

forces? – a drag and drop activity asking pupils to add force arrows to various pictures, and to name the forces concerned. Note that once an arrow or a label has been placed it cannot be moved until answers have been checked.

3: Contact and non-contact forces card sort AB/ATAfl The AT document link on page 150 opens Contact and non-

contact forces – a card sort activity asking pupils to classify forces as contact forces or non-contact forces. Pupils could work on this individually or in small groups.

4: Thinking about forces (AT)• OOO: friction, gravity, magnetism. (Possible answers: friction is

the only contact force and is the only one that always tries to slow things down; magnetism is the only one that can push or pull; gravity is the only one that gives us weight.)

• CAP: a bicycle is slowing down. (Possible answers: it is going up a hill; the rider has stopped pedalling; it is going into the wind and air resistance is slowing it down; it has gone into water and water resistance on the wheels is slowing it down.)

• PMI: gravity on Earth should be weaker. (Possible answers:P – it would be easier to pick things up; M – things would blow away more easily on windy days; I – which sports records would change?)

The second AT presentation link on page 151 opens Thinking about forces – a PowerPoint presentation version of this task.

5: I can ... cloze exercise AB/ATAfl The AT document link on page 151 opens a cloze exercise

summarising the content of pages 150–151. There is also an AT presentation version with answers.

Homework tasks

1: Worksheet 7Ka(4) provides questions and a wordsearch to help pupils to learn the names of the different forces discussed in this topic.

2: Worksheet 7Ka(5) provides a reverseword, in which pupils are asked to write a set of clues for an already-completed crossword.

3: Worksheet 7Ka(6) looks at how bathroom scales work. It will be helpful, but not essential, if pupils have watched Explaining 3.

7Ka Sport and forces

UNIT12.indd 270 12/3/08 15:07:37


Pupil’s materials


Friction Must/Should PB p152–153 Classwork Explaining 2

7Kb Quick check Must/Should ASP Classwork Plenary 3

7Kb Word Sheet Must/Should ASP Homework

7Kb(1) Friction Must CHAP Access Explaining 2

7Kb(2) Investigating friction 1 Must CHAP Practical Exploring 1

7Kb(3) Investigating friction 2 Should/Could CHAP Practical Exploring 1

7Kb(4) Friction – true or false? Must/Should CHAP Classwork Starter 2, Plenary 4

7Kb(5) Friction and sport Must CHAP Homework Homework 1

7Kb(6) Mountain bikes Should CHAP Homework Homework 2

7Kb(7) A curling question Could CHAP Homework Homework 3

SS1–4 Thinking Skills Must/Should CHAP Skills sheet Starter 1

SS28 Bar charts Must/Should CHAP Skills Sheet Exploring 1

SS29 Line graphs Must/Should CHAP Skills Sheet Exploring 1


(1) explain that friction is a force between two surfaces touching each other;

(2) explain that friction slows things down(3) recall that rough surfaces produce more friction than smooth

surfaces(4) describe some situations in which friction is helpful and

some where it is not(5) recall that air resistance and water resistance are forms of

friction.Most pupils should:

(6) describe the effects of friction(7) explain that friction can be reduced by adding a lubricant(8) be able to design a fair test to investigate friction(9) apply ideas about forces and friction in different contexts.

Correctly use the words lubricant, lubrication.Some pupils could:

(10) recall that materials such as PTFE produce very little friction and are used in making non-stick pans.

Topic notesTargets for the lesson can be accessed via the ActiveBook or ActiveTeach from the link next to the initiator question.

Exemplar topic plans*

MUST*

PB pages 152–153

Starter 2Explaining 1Explaining 2Explaining 3Plenary 2Explaining 5Plenary 3

Explaining 4Exploring 1Plenary 5Homework 1

SHOULD*

PB pages 152–153

Starter 1Starter 2Explaining 1Explaining 2Explaining 3Explaining 5Plenary 1


COULD*

PB pages 152–153

Starter 1Starter 2Explaining 1Explaining 2Explaining 3Explaining 5Plenary 1


SHOULD 2 Yr KS3**

PB pages 149–153

7Ka Starter 27Ka Starter 57Ka Exploring 37Ka Explaining 27Kb Plenary 27Kb Explaining 27Kb Explaining 57Kb Plenary 1

7Kb Starter 17Kb Explaining 47Kb Exploring 17Kb Plenary 47Kb Homework 3

* It is envisaged that you may want to spend twice the usual amount of time on this topic for all pupils – there are two topic plans for each level, to be used consecutively.** This table is repeated in 7Ka.

7Kb Friction

7Kb

UNIT12.indd 271 12/3/08 15:07:38


Starters

1: Thinking about friction (AT)Afl Give pupils the following thinking skills questions to fi nd out

what they already know about friction. You may wish to note any misconceptions indicated by pupils’ answers, and revisit these later in the lesson when pupils may be able to correct their own misconceptions.

• PMI: there should be no friction. (Possible answers: P – cars would need smaller engines; things wouldn’t wear away; M – cars would not be able to stop; you would have to drink through a straw because you couldn’t pick up a glass; I – what would walking be like if there were no friction?)

• CAP: reasons why a bicycle might not go very fast. (Possible answers: the axles need lubricating; the brakes are catching; there is a strong wind blowing; the cyclist is not pedalling hard.)

The second AT presentation link on page 152 opens Thinking about friction – a PowerPoint presentation version of this task.

2: Friction – true or false?Afl Use the card sort activity provided in Worksheet 7Kb(4) to

fi nd out what pupils know about friction. If the sorted piles of cards can be kept until the end of the lesson, pupils could revisit this activity to see if any of their ideas have changed. This activity will be quicker if pupils are provided with the statements already cut up into separate cards.

Exploring tasks

1: Practical: Factors affecting frictionDiscuss with pupils the factors that could affect friction, and then ask pupils to plan their own investigation. You may wish to carry out Explaining 4 (an interactive activity asking pupils to spot mistakes in an investigation) or Explaining 5 (a practical demonstration with deliberate mistakes) to help them to think about fair testing before they plan their own investigation.

Pupils could investigate the size of the area in contact, the roughness of the surface, the force with which the two surfaces are pushed together, or the speed at which the block is pulled. The apparatus needed will depend on the pupils’ plans, but the list below should cover most eventualities.

This practical can be used to carry out an AT1 Investigation. A sheet of level descriptions is provided on pages 286–287 of the ASP. Note that using Worksheet 7Kb(2) will limit pupils’ possible marks in the planning strand.

• Must: pupils follow the directions on Worksheet 7Kb(2).• Should/Could: pupils can plan their own investigation using the

hints on Worksheet 7Kb(3). Skills Sheets 28 and 29 may be of use when presenting results.

Take care that the block does not fall off the edge of the bench.

Resources (per group)Blocks of wood of different sizes fi tted with hooks; force meter; ramp; sheets of paper and sandpaper of different grades; drawing pins; set of slotted masses; stop clock; Worksheets 7Kb(2) or 7Kb(3); Skills Sheets 28, 29

Topic task plannerUse these tasks to adapt the exemplar topic plans to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’). AT or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use.Also consider using one of the plenaries from the previous topic as a starter task in this topic.


Starter 1 M/S 4–5 Classwork 1, 2, 4, 6, 7 PLTS (Ct) 1b

Starter 2 M/S 4–5 Classwork 6 1b c

Exploring 1 M/S/C 4–6 Practical 1, 3, 7, 8 PLTS (Ie, Sm), Num (M, T, B, L)

1a, 1b 1a, 1b, 1c, 2a, 2b, 3a

1b a, b

Explaining 1 M/S 4–5 Practical 7 1b

Explaining 2 M/S 4–5 Classwork 1–7 2a 1b c

Explaining 3 M/S 4–5 Classwork 3, 6, 7 2a 1b c, k

Explaining 4 M/S 4–5 Classwork 8 2b 1b

Explaining 5 M/S 4–5 Practical 8 2b 1b

Plenary 1 S 4–5 Classwork 1–7 3a 1b

Plenary 2 M 4 Classwork 1, 6 1b c

Plenary 3 M/S 4–6 Classwork 1–7 PLTS (Ep, Tw) 1b c

Plenary 4 M/S 4–5 Classwork 6 PLTS (Rl) 1b c

Plenary 5 M 4–5 Classwork 1–7 Lit (WF) 1b

Homework 1 M 4 Homework 1, 2, 4, 5 1b c

Homework 2 S 5 Homework 3, 4, 6, 7, 9 Lit (RR) 1b c

Homework 3 C 5–6 Homework 9 Num (C, L) 3a 1b c

Homework 4 C 5–6 Homework 10 Lit (RR) 2a 2b, 3a 1b c

7Kb Friction

7Kb

UNIT12.indd 272 12/3/08 15:07:39


Explaining tasks

1: Practical: Lubrication demonstrationPossible demonstrations are pulling an ice cube and a block of wood along the bench pointing out that the water from melting ice produces a lubricant, or use oil or washing up liquid to provide a lubricating fi lm between the bench and a block of wood being pulled along it. You may wish pupils to push the blocks so they can feel the effects of the lubricant themselves, or use a force meter to quantify the different forces needed to pull lubricated and unlubricated blocks.

Pupils can also be reminded of the practicals they carried out in Topic 7Ka with the block of wood and ice cube, or the two types of string (both parts of 7Ka Exploring 1), and asked why they think the objects behaved differently.

Clear up any spilled liquids.

ResourcesIce cube; wooden block; oil or washing up liquid; force meter.

2: Pupil’s Book pages 152–153 (AT)This looks at friction and its effects, and introduces the idea of lubrication. Worksheet 7Kb(1) is the Access Sheet.

Many pupils will have a good practical understanding of friction through their own experiences at home and in school, yet they may not necessarily relate these experiences to the force of friction.

The usefulness of friction can be introduced by talking about walking on ice or packed snow, about the use of brakes in cars and on bicycles, and by discussing how pencils write.

• Must: it may be best to use this task together with Explaining 3, which uses various videos to illustrate the points. For example, use the AT to show pupils one paragraph or one photograph at a time, and discuss with them what the pictures are showing, then play the relevant video.

3: Using friction AT• The fi rst AT video link on page 152 opens Using friction in

climbing – a video showing Jim talking about the ways in which friction is useful in climbing, and when it is not useful.

• The second AT video link on page 152 opens Friction and bicycles – a video showing Jim talking about the uses of friction in bicycles, and the factors which reduce useful friction. It also shows how certain parts of bicycles are lubricated to reduce friction. Note that the presenter talks about ‘pressure’ but really means ‘force’. Challenge higher-attaining pupils to spot the mistake.

4: Measuring friction ATAfl The AT animation link on page 152 opens Measuring friction

– an animation showing an investigation into friction, which includes mistakes that mean the test shown is not fair. Ask pupils to watch the animation and identify the mistakes. It may be necessary to view it more than once.

The mistakes are:• on the second trial the pupil forgets to put the weight on the

block• on the third trial the pupil forgets to use the plank and uses the

table top instead• on the fourth trial the block is not pulled at a steady rate• on the fi fth trial the plank is raised at one end.

5: Practical: Spot the mistakeAfl This is a practical alternative to Explaining 2 (spotting mistakes

in an investigation into friction). Demonstrate how to carry out an investigation, but include deliberate errors such as changing two variables at once. Ask pupils to point out the errors, and discuss ways of improving the method. Take the opportunity to discuss the need for repeat readings. The friction could be measured by fi nding the force needed to pull a block along at a steady speed, or fi nding the time taken for a block to slide down a ramp. The advantages and disadvantages of each method could be discussed. This task could be used to help pupils to plan their own investigation into the factors affecting friction (Exploring 1).

Take care that the block does not fall off the edge of the bench.

ResourcesBlocks of wood of different sizes fi tted with hooks; force meter; ramp; sheets of paper and sandpaper; drawing pins; set of slotted masses; stop clock.

Plenaries

1: Ten facts about frictionConsolidate the work of this topic by asking pupils to produce an information card with ‘Ten facts about friction’. They could do this individually or in groups, and then share their facts with the rest of the class. If time permits they could present their facts as an electronic presentation.

2: Sources of friction ATThe AT video link on page 153 opens Friction – a video showing eight different clips involving friction. Ask pupils to identify the sources of friction in each clip, and to say whether the friction is useful or not. You could extend this by also asking them to comment on how the friction is increased or reduced in each case.

3: Quick CheckAfl Give pupils copies of the Quick Check sheet and ask them to

discuss the answers in groups. Give them fi ve minutes to do this, then ask groups to report back on one of the pictures. You could also ask groups to think up a situation of their own, and to describe the situation, helpful and unhelpful friction, and how the friction could be controlled.

4: Friction – true or false revisitedAfl If you have kept the sorted cards from Starter 2, ask pupils

to look at their sorted cards and to move any cards that they now think are in the wrong pile. Ask them to explain any changes they have made, and why they made them.



Homework tasks

1: Worksheet 7Kb(5) provides questions to help to consolidate the work in this topic.

2: Worksheet 7Kb(6) provides questions about friction and lubrication.

3: Worksheet 7Kb(7) describes an investigation into friction, and asks pupils to plot the results and draw conclusions.

4: Ask pupils to fi nd out about Tefl on® and its uses. Pupils could report back verbally in the next lesson, or could produce a short report, a poster or a presentation to communicate their fi ndings.

Friction 7Kb

7Kb

UNIT12.indd 273 12/3/08 15:07:40


Pupil’s materials


That fl oating feeling Must/Should PB p154–155 Classwork Explaining 1

Focus on: Safe sports Should/Could PB p156–157 Classwork Explaining 5

7Kc Quick Check Must/Should ASP Classwork Plenary 1

7Kc Word Sheet Must/Should ASP Homework

7Kc(1) That fl oating feeling Must CHAP Access Explaining 1

7Kc(2) Safe sports Should CHAP Access Explaining 5

7Kc(3) Floating, sinking and density Must/Should CHAP Practical Exploring 2

7Kc(4) Upthrust in different liquids Should CHAP Practical Exploring 3

7Kc(5) Floating questions Must CHAP Homework Homework 1

7Kc(6) Safe kayaks Should CHAP Homework Homework 2

7Kc(7) Archimedes Could CHAP Homework Homework 3

SS1–4 Thinking Skills Should CHAP Skills Sheet Plenary 2

SS22 Measuring volumes Must CHAP Skills Sheet Exploring 2

SS35 Evaluating Should CHAP Skills Sheet Exploring 3


(1) recall that upthrust is a force that pushes up in water or air(2) explain that an object will fl oat when the upthrust and

weight are balanced.Most pupils should:

(3) recall that the amount of upthrust depends on the liquid the object is fl oating in

(4) describe how to measure the volume of regular and irregular objects

(5) describe how to calculate density(6) explain how to work out if something will fl oat by comparing

the density of the object and the liquid(7) apply their knowledge of friction, forces and fl oating to

outdoor activities.Correctly use the words displacement, density.

Some pupils could:(8) recall that Archimedes was the fi rst person to explain why

objects fl oat.



MUST

PB pages 154–155

Starter 1Exploring 1Exploring 2Exploring 4Explaining 1Plenary 1Plenary 3Homework 1

SHOULD

PB pages 154–155

Starter 1Exploring 2Exploring 3Explaining 1Explaining 2Explaining 3Explaining 4Plenary 1Homework 2

COULD

PB pages 154–157

Starter 1Exploring 2Exploring 3Explaining 1Explaining 2Explaining 3Explaining 4Explaining 5Plenary 1Homework 3

SHOULD 2 Yr KS3*

PB pages 154–159

7Kc Plenary 17Kc Exploring 27Kc Explaining 17Kc Plenary 17Kd Explaining 17Kd Exploring 17Kd Plenary 17Kc Homework 27Kd Homework 2

* This table is repeated in 7Kd.

7Kc That fl oating feeling

7Kc

UNIT12.indd 274 12/3/08 15:07:41


Starters

1: Brainstorm fl oatingAfl Brainstorm pupils’ ideas about fl oating. Elicit suggestions for

things that fl oat and sink, and ask them to speculate why some things fl oat and some things sink. Ask if they think the liquid used makes any difference. If pupils’ ideas can be recorded it will be useful to revisit their ideas at the end of the lesson to see if any of their ideas have changed, or to allow them to identify what they have learned during the lesson.

2: Practical: Float or sink?Show pupils a range of materials, and ask them to suggest what will happen if they are put into water. Ask how they can predict which ones will fl oat or sink, and demonstrate – particularly if they have made incorrect predictions. Pupils are likely to predict that ‘heavy’ things will sink. If possible, have a small dense object (such as a ball bearing) and a large piece of less dense material (such as a piece of wood – but check it is not a dense hardwood that will sink) and show that the wood is heavier than the ball bearing, but still fl oats. Elicit the idea that it is the mass for a particular size that matters.

Clear up any spills straight away.

ResourcesLarge beaker or glass bowl full of water; variety of objects/materials, including one object that will fl oat that is heavier than one of the non-fl oating objects (e.g. a block of wood and a small ball bearing).

Exploring tasks

1: Practical: Feeling upthrustPresent pupils with a range of objects such as expanded polystyrene, or sealed, empty plastic drinks bottles. Submerge them

in a sink or bowl of water, and let pupils feel the force required to hold them under water.


Resources (per group)Bowl of water or access to a sink; sealed empty plastic drinks bottle; expanded polystyrene.

2: Practical: Floating, sinking and densityPupils measure the upthrust on various objects by fi nding the difference between their weight in air and their weight in water. They also calculate the density of each object, and investigate the link between density and fl oating/sinking. If irregular shaped objects are used, pupils may need help measuring the volumes (see Skills Sheet 22). Worksheet 7Kc(3) provides instructions.


Resources (per group)Samples of different materials (include wood, expanded polystyrene, and at least two different metals); ruler; calculator; bowl; water; force meter; Worksheet 7Kc(3). Optional: Skills Sheet 22.

3: Practical: Upthrust in different liquidsPupils investigate the amount of upthrust provided by different liquids by measuring the change in weight when an object is suspended in the liquid. The choice of object will depend on the liquids being used – choose something which does not quite fl oat in the densest liquid. A fair test actually only requires the same volume of object to be used each time – with higher-attaining pupils you could use objects of the same volume but different densities and compare results. You could limit the range of liquids supplied to varying concentrations of salty water.

Topic task plannerUse these tasks to adapt the exemplar topic plans to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’.) AT or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use.Also consider using one of the plenaries from the previous topic as a starter task in this topic.


Starter 1 M/S 4–6 Classwork 1–3 PLTS (Ep, Ct) 1b c

Starter 2 M/S 4–6 Practical 2, 5 1a 1b

Exploring 1 M/S 4 Practical 1 1a, 1c 1b a

Exploring 2 M/S 5–6 Practical 1, 2, 4, 5, 6 PLTS (Tw), Num (M, C, T)

1a, 1b 1a, 1c, 2a 1b a, b

Exploring 3 S 5–6 Practical 1–6 PLTS (Tw), Num (M, C, T)

1a, 1b 1a, 1c, 2a 1b a, b

Exploring 4 M 4–5 Practical 1, 2 PLTS (Ct, TW) 1a, 1b 1c 1b

Explaining 1 M/S 5–6 Classwork 1–6 1b

Explaining 2 S 5–6 Classwork 3, 5, 6 1b c

Explaining 3 S 5–6 Classwork 3, 5, 6 2b 1b

Explaining 4 S 6 Classwork 3, 6 Lit (EC) 2a, 2b 1b c

Explaining 5 C 4–6 Classwork 7 2a 1b 1b c, e, j, k

Explaining 6 M/S 4–6 Classwork 1, 2, 6, 7 2a 1b 1b c

Plenary 1 M/S 4–6 Classwork 2, 6 PLTS (Rl) 1b

Plenary 2 S 4–6 Classwork 1–6 PLTS (Ct) 1b


Homework 1 M 4–5 Homework 1, 2 Num (C) 1b

Homework 2 S 4–5 Homework 1, 6, 7 1b

Homework 3 C 6 Homework 1, 2, 6, 8 3a 1b h

That fl oating feeling 7Kc

7Kc

UNIT12.indd 275 12/3/08 15:07:43


Encourage pupils to compare their results with each other, and use the comparisons as a basis for discussing the accuracy of their results. Skills Sheet 35 may help pupils with this evaluation process.

Clear up any spills straight away. Take care with any fl ammable liquids used. Check hazcards to make sure no harmful liquids are used.

Resources (per group)Force meter; string; selection of liquids (e.g. water, cooking oil, salty water); object small enough to fi t in beaker that does not quite fl oat in the densest liquid; beaker; balance; Worksheet 7Kc(4). Optional: Skills Sheet 35.

4: Practical: Plasticine boatsGive each working group a piece of Plasticine®, and ask them to make it into a boat. This will be trial and error, and small masses (10 to 100 g stacking masses would do) should be provided so they can test the load-carrying capacity of their boats. Challenge pupils to make the best boat out of a limited quantity of Plasticine®.


Resources (per group)Lump of Plasticine®; 10–100 g masses; large empty ice cream or margarine tub; or other suitable water container.

Explaining tasks

1: Pupil’s Book pages 154–155 (AT)This looks at fl oating and density. Worksheet 7Kc(1) is the Access Sheet.

• Must: use the AT to display the artwork and photos on this page one at a time, and discuss what each one shows. Ask pupils the questions verbally, and discuss answers if necessary.

2: Ships and balloons ATThe AT animation link on page 155 opens Ships and balloons – this explains why ships and hot air balloons fl oat, even though the materials from which they are made are denser than the medium in which they fl oat.

3: Different densities ATThe second AT presentation link on page 155 opens Different densities – a presentation that shows the effects of the density of both the fl uid and the fl oating object.

4: The Plimsoll line AB/ATThe fi rst AT document link on page 155 opens The Plimsoll line – a worksheet looking at the reason why ships have Plimsoll lines on them.

5: Pupil’s Book pages 156–157 (AB/AT)This looks at some ways in which climbers stay safe, and on how risks in outdoor activities can be assessed. The material on these pages helps to reinforce learning from this topic and Topic 7Kb. Worksheet 7Kc(2) will help some pupils to access the information on these pages.

• The AT video link on page 156 opens Climbing safety – a video which shows Tim describing some of the equipment climbers use to make sure that they stay safe.

6: Kayaks AB/ATDiscuss how sports such as kayaking can be made safer using ideas about fl oating. Note that Worksheet 7Kc(6) also looks at safety when kayaking, but can be done without having carried out this task.

• The second AT document link on page 155 opens Sea kayak safety – a worksheet that asks pupils to explain some of the safety guidance given to sea kayakers, and to relate it to what they know about fl oating and sinking.

Plenaries

1: Quick CheckAfl Use the Quick Check, which contains pairs of statements for

pupils to rank as true or false. They are asked to correct any false statements. Using their corrected statements they are then asked to decide whether or not the second statement of each pair is an explanation for the fi rst one. Pupils could be asked to give a CRI score (see page 20) for each answer. Allow pupils to work on this singly or in small groups, and then report back to compare answers.

2: Thinking about fl oating (AT)• PMI: all ships should be made from wood. (Possible answers:

P – all ships would be safer as they would fl oat anyway; M – it would be diffi cult to make very large ships; I – is wood as strong as other materials?)

• PMI: everything should be able to fl oat. (Possible answers:P – no-one would drown, and no boats would sink;M – everything would fl oat away in a fl ood; I – what would happen in the sea if rocks and sand at the bottom of the sea fl oated?)

• CAP: an object fl oats. (Possible answers: the object is less dense than water; the object is denser than water but is fl oating in a liquid with an even greater density; the object is shaped so that it has air spaces so its overall density is less than water.)

The fi rst AT presentation link on page 155 opens Thinking about fl oating – a PowerPoint presentation version of this task.

3: I can ... cloze exercise AB/ATAfl The third AT document link on page 155 opens a cloze

exercise summarising the content of pages 154–155. There is also an AT presentation version with answers.

Homework tasks

1: Worksheet 7Kc(5) provides questions about fl oating and sinking to help consolidate the work in this topic.

2: Worksheet 7Kc(6) provides questions on buoyancy in relation to kayaks.

3: Worksheet 7Kc(7) extends ideas about fl oating and sinking to discuss Archimedes’ work on fl oating.

7Kc That fl oating feeling

7Kc

UNIT12.indd 276 12/3/08 15:07:44


Pupil’s materials


Balancing act Must/Should PB p158–159 Classwork Explaining 1

7Kd Quick Check Must/Should ASP Classwork Plenary 1

7Kd Word Sheet Must/Should ASP Homework

7Kd(1) Balancing act Must CHAP Access Explaining 1

7Kd(2) Make a force meter 1 Must CHAP Practical Exploring 1

7Kd(3) Make a force meter 2 Should CHAP Practical Exploring 1

7Kd(4) Forces and movement Must/Should CHAP Classwork Explaining 4

7Kd(5) Stretching springs 1 Must CHAP Classwork Explaining 5

7Kd(6) Stretching springs 2 Should CHAP Classwork Explaining 5

7Kd(7) Changing speed 1 Must CHAP Homework Homework 1

7Kd(8) Changing speed 2 Should CHAP Homework Homework 2

7Kd(9) Climbing ropes Could CHAP Homework Homework 3


(1) describe the difference between balanced and unbalanced forces

(2) describe what will happen in simple situations involving balanced or unbalanced forces

(3) recall that ideas about forces have changed as new experiments have been carried out.Correctly use the words balanced forces, unbalanced forces.

Most pupils should:(4) describe some differences between modern ideas about

forces and older ideas, and the role of experimentation in changing ideas

(5) recall that a spring stretches evenly up to a certain point(6) describe how this principle is used in many force meters

(also known as newton meters).Correctly use the words elastic, stationary.

Some pupils could:(7) recall that springs have an elastic limit beyond which

stretching is non-uniform(8) explain some applications of elasticity (other than force

meters).

Topic notes• Targets for the lesson can be accessed via the ActiveBook or

ActiveTeach from the link next to the initiator question.• Balanced forces have been mentioned already in the unit (e.g. in

terms of something fl oating if the upthrust balances the weight). The aim of this topic is to formalise this concept, and to get pupils to think about the forces providing the ‘balancing’ for stationary objects.


MUST

PB pages 158–159

Starter 1Starter 3Exploring 1Explaining 1Explaining 2Plenary 4Homework 1

SHOULD

PB pages 158–159

Starter 1Exploring 1Exploring 2Explaining 1Explaining 2Plenary 1Homework 2

COULD

PB pages 158–159

Starter 1Exploring 1Exploring 2Explaining 1Explaining 2Plenary 1Homework 3

SHOULD 2 Yr KS3*

PB pages 154–159

7Kc Plenary 17Kc Exploring 27Kc Explaining 17Kc Plenary 17Kd Explaining 17Kd Exploring 17Kd Plenary 17Kc Homework 27Kd Homework 2

* This table is repeated in 7Kc

7Kd Balancing act

7Kd

UNIT12.indd 277 12/3/08 15:07:44


Starters

1: Practical: Balanced forcesDemonstrate various situations where forces are balanced. Discuss the types of forces, and how pupils know they are balanced. Suitable demonstrations include: tie a paper clip to the base of a clamp stand using a piece of cotton thread, and position a magnet above it so that the paper clip appears to be suspended; a helium or hydrogen fi lled balloon tied to a mass to stop it rising; an object resting on a table; an object suspended from a string; a tug of war or arm wrestling contest (ask two sensible pupils to cooperate).

Discuss what forces are present and point out that there are pairs of forces balancing each other. This could lead into work on stretching materials by showing a mass attached to a rubber band, and asking pupils what would happen if a larger mass were added, or if you used a thicker rubber band.

Ensure there are no fl ames in the laboratory if a hydrogen fi lled balloon is being used.

ResourcesClamp and stand; cotton thread; magnet; balloon fi lled with helium or hydrogen (on a string); string; masses or other objects.

2: Forces on pupilsAsk pupils to describe the forces on them while they are sitting or standing, or while riding a bike etc. Elicit ideas about what forces are necessary to keep something moving. Pupils can jot down their ideas and revisit them at the end of the lesson.

3: What do forces do? AB/ATThe AT document link on page 158 opens What do forces do? – a document with illustrations of various situations involving forces. Ask pupils to comment on the relative sizes of the different forces, and what will happen in each case. This could be done as a class discussion, or pupils could write their answers down. Pupils can revisit their answers at the end of the topic to see if any of their ideas have changed (see Plenary 2).

It is also worth reminding pupils of the convention that forces can be represented by arrows showing the direction in which they are acting, and that the size of the arrow indicates the size of the force.

Exploring tasks

1: Practical: Making a force meterPupils ‘calibrate’ a spring by producing a graph of weight against length, and use it to weigh another object. Before carrying out this practical the maximum load for the springs in use must be determined – the mass values on Worksheet 7Kd(2) may need to be changed if 5 N is beyond the elastic limit of the springs. If insuffi cient G-clamps are available to fasten stands to the bench, place a large mass on the base of each stand to stop it toppling over. Ensure that objects to be weighed are within the range covered in the experiment. This practical could be presented as a contest to see who can fi nd the weight of an object most accurately.

Topic task plannerUse these tasks to adapt the exemplar topic plans to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’). AT or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use.Also consider using one of the plenaries from the previous topic as a starter task in this topic.


Starter 1 M/S 4–5 Practical 1, 2 1a 1b

Starter 2 M/S 4–5 Classwork 1, 2 PLTS (Ep) 1b

Starter 3 M 4 Classwork 1, 2 1b

Exploring 1 M/S/C 4–7 Practical 1, 2, 5–7 PLTS (Tw), Num (M, C, T, L) 1a, 1b 1a, 1b, 1c, 2a, 2b, 3a

1b a, b

Exploring 2 S 4–7 Practical 1, 2, 5, 6 PLTS (Tw), Num (M, C, T, L) 1a, 1b 1a, 1b, 1c, 2a, 2b, 3a

1b a, b

Exploring 3 C 6–7 Practical 1, 2, 5, 6 PLTS (Tw), Num (M, C, T, L) 1a, 1b 1a, 1b, 1c, 2a, 2b, 3a

1b a, b

Explaining 1 M/S 4–5 Classwork 1, 2, 5, 6 Lit (WF) 1b c

Explaining 2 S 4–5 Classwork 1, 2, 5, 6 1b

Explaining 3 M/S 4–5 Classwork 5, 6 Num (L), ICT (SS) 1b 2a, 3a 1b

Explaining 4 M/S 4–6 Classwork 3, 4 3a h

Explaining 5 M/S 4–5 Classwork 5 Num (L) 3a 1b

Plenary 1 M/S 4–5 Classwork 1–4, previous topics PLTS (Ct) 1b

Plenary 2 M 4 Classwork 1, 2 PLTS (Rl) 1b

Plenary 3 M/S 4–5 Classwork 1–8 PLTS (Rl) 1b


Homework 1 M 4–5 Homework 1, 2 1b c

Homework 2 S 4–5 Homework 1, 2 1b c

Homework 3 C 4–6 Homework 6 Lit (EC) 2a 1b

7Kd Balancing act

7Kd

UNIT12.indd 278 12/3/08 15:07:46


• Must: pupils follow the directions on Worksheet 7Kd(2).• Should: pupils follow the directions on Worksheet 7Kd(3).• Could: ask pupils to fi nd out what happens if too much force is

applied to a spring. Eye protection will be needed in this case, and it is advisable to stand a waste bin or bucket with newspapers beneath the masses to keep toes out of the way and to deaden the noise if the spring breaks.

Wear eye protection if springs are to be stretched to breaking point. Stand a waste bin or bucket lined with newspaper beneath the masses to ensure that they cannot fall on pupils’ feet. Clamp the base of the stand to the bench so it cannot fall over.

Resources (per group)Retort stand and 2 clamps; metre rule; spring; mass holder and masses (100 g to 1000 g); G-clamp; object to weigh; graph paper; Worksheet 7Kd(2) or 7Kd(3). Optional: box with newspaper; eye protection.

2: Practical: Stretching elastic bandsThis practical is best done as a follow-up to Exploring 1. Ask pupils to fi nd out if elastic bands stretch in a similar fashion to springs. Ask pupils to repeat their readings to provide more accurate measurements, and then to plot the results for springs and elastic bands on the same axes. Pupils should be encouraged to describe the differences between the two lines, and what this means in terms of the different way that springs and elastic bands stretch.

Wear eye protection if elastic bands or springs are to be stretched to breaking point. Stand a waste bin or bucket lined with newspaper beneath the masses to ensure that they cannot fall on pupils’ feet. Clamp the base of the stand to the bench so it cannot fall over.

Resources (per group)Retort stand and 2 clamps; metre rule; spring; mass holder and masses (100 g to 1000 g); G-clamp; object to weigh; elastic band; graph paper; box with newspapers; eye protection.

3: Practical: Two springsThis practical is best done as a follow-up to Exploring 1. Ask pupils what they think will happen if two similar springs are used together, either end to end or next to each other, and to explain their reasoning. Pupils can then plan and carry out a quick investigtion to test their predictions. They should fi nd that two springs fastened end to end produce twice the extension because the full force is applied to both springs and so both stretch. With two springs next to each other (as shown below), the extension should be half that of a single spring, as each spring is supporting only half of the weight.

Wear eye protection if springs are to be stretched to breaking point. Stand a waste bin or bucket lined with newspaper beneath the masses to ensure that they cannot fall on pupils’ feet. Clamp the base of the stand to the bench so it cannot fall over.

Resources (per group)Retort stand and 2 clamps; metre rule; 2 similar springs; short length of dowel; mass holder and masses (100 g to 1000 g); G-clamp; graph paper; box with newspapers; eye protection.

Explaining tasks

1: Pupil’s Book pages 158–159 (AT)This looks at balanced forces and how force meters work. Worksheet 7Kd(1) is the Access Sheet.

• Must: use the AT to look at the drawings on page 158 and discuss what is happening in terms of balanced forces. Ask pupils the questions in the book verbally. The material on force meters could be omitted if Explaining 2 (discussing how force meters work) is going to be used.

• The AT animation link on page 158 opens Balanced and unbalanced forces – an animation that helps to explain the effects of balanced and unbalanced forces.

2: Balanced forces and weighing objects (AT)If Exploring 1 has been carried out, consolidate ideas about balanced forces by discussing how the force in a spring or elastic band increases as it stretches, and how the spring stops stretching when the force provided by it balances the weight of the object suspended from it.

• The AT animation link on page 159 opens Weighing objects – an animation that illustrates the role of balanced forces in a force meter.

3: A spring experiment AB/ATThe AT spreadsheet link on page 159 opens A spring experiment – a spreadsheet with the results of an investigation using two different springs. This can be used in place of Exploring 1 if time is short, or can be used as additional reinforcement of the results expected from such an investigation or to give pupils practice in using a spreadsheet package for graph plotting. The spreadsheet includes some questions.

4: Aristotle and GalileoWorksheet 7Kd(4) looks at Aristotle’s ideas about forces on moving objects, and contrasts his ideas and methods with those of Galileo.

• Must: read through the sheet with pupils and discuss the ideas.• Should: pupils could work through the sheet alone or in pairs,

before discussing answers to the questions.

5: Stretching springsWorksheets 7Kd(5) and 7Kd(6) provide data from an experiment with springs, for pupils to plot graphs and draw conclusions. These can be used if time or facilities are not available to carry out the practical on making a force meter described in Exploring 3.

Balancing act 7Kd

7Kd

UNIT12.indd 279 12/3/08 15:07:47


Plenaries

1: Quick CheckAfl Give pupils copies of the Quick Check sheet and ask them

to write questions to fi t the answers given. Pupils should be encouraged to think of more than one possible question that would result in the given answer. Note that this activity revises and reinforces work from Topic 7Ka as well as this topic.

• Must: pupils would not be expected to recall the meaning of elastic, so they could omit the last question.

2: What do forces do revisited AB/ATAfl The AT document link on page 158 opens What do forces

do? – a document with illustrations of various situations involving forces. If pupils wrote down answers to the questions on this sheet in Starter 3, ask them to look at their answers and to amend any that they now think may be incorrect. If pupils have not already used the sheet, ask them to comment on the relative sizes of the different forces and what will happen in each situation. Give pupils a few minutes to jot their ideas down, and then ask them to report back to the class.

3: Forces on pupils revisitedAfl Revisit the notes that pupils made in the brainstorming session

in Starter 2. Ask them to amend their notes to refl ect what they have learnt during the lesson. You could also ask selected pupils to tell the rest of the class one new thing they have learnt.



Homework tasks

1: Worksheet 7Kd(7) provides questions on balanced and unbalanced forces.

2: Worksheet 7Kd(8) provides questions on balanced and unbalanced forces.

3: Worksheet 7Kd(9) looks at how climbing ropes act to stop a falling climber gradually.

7Kd Balancing act

7Kd

UNIT12.indd 280 12/3/08 15:07:47


Pupil’s materials


The need for speed Must/Should PB p160–161 Classwork Explaining 1

Safety standards Should/Could PB p162 Classwork Explaining 3

7K Quick Quiz Must/Should ASP Classwork Plenary 3

7K Quick Quiz Answer Sheet Must/Should ASP Classwork Plenary 3

7K End of Unit Test Must/Should ASP Classwork Plenary 7

7K Level Ladder Must/Should ASP Classwork Plenary 8

7Ke Quick Check Must/Should ASP Classwork Plenary 2

7Ke Word Sheet Must/Should ASP Classwork

7Ke(1) The need for speed Must CHAP Access Explaining 1

7Ke(2) Match the speeds! Must/Should CHAP Classwork Starter 3

7Ke(3) The Highway Code Should/Could CHAP Classwork Exploring 1

7Ke(4) Speed check Must CHAP Homework Homework 1

7Ke(5) Bungee jumping Should CHAP Homework Homework 2

7Ke(6) Speed records Could CHAP Homework Homework 3

SS29 Line graphs Should CHAP Classwork Exploring 1


(1) state that speed is how far an object moves during a set period of time

(2) recall that speed is normally measured in m/s, km/h or mph.Correctly use the words km/h, m/s, mph, speed.

Most pupils should:(3) interpret a simple distance–time graph(4) explain what thinking distances, braking distances and

stopping distances are, and how they are affected by road conditions and driver alertness

(5) suggest some reasons why safety standards are needed in certain situations.Correctly use the words braking distance, distance–time graph, stopping distance, thinking distance.

Some pupils could:(6) apply ideas about forces and times to athletics records.


Be prepared: 7KeExploring 2: road safety survey trip.


MUST

PB pages 160–162

Starter 1Explaining 1Explaining 2Exploring 2Explaining 3Plenary 4Plenary 8Homework 1

SHOULD

PB pages 160–162

Starter 1Explaining 1Exploring 1Explaining 2Explaining 3Plenary 4Plenary 5Plenary 8Homework 2

COULD

PB pages 160–162

Starter 1Explaining 1Exploring 1Explaining 2Explaining 3Plenary 4Plenary 5Homework 3

SHOULD 2 Yr KS3

PB pages 160–162

7Ke Starter 17Ke Explaining 17Ke Exploring 17Ke Explaining 27Ke Explaining 37Ke Plenary 47Ke Plenary 57Ke Plenary 87Ke Homework 2

7Ke The need for speed

7Ke

UNIT12.indd 281 12/3/08 15:07:48


Starters

1: Brainstorm speedAfl Ask pupils to jot down their ideas about speed, what it means,

its units of measurement and some examples of fast and slow moving objects. They can then be asked to contribute ideas to a class brainstorm.

It may help to make notes on the board that can be referred to later in the topic. This is particularly useful if any misconceptions are apparent in pupils’ answers – you may wish to leave them initially, and revisit the results of the brainstorm later in the topic when pupils may be able to correct their own misconceptions.

2: Speed limitsAsk pupils what a speed limit is, and what the units are for the speed limit numbers given on road signs. Ask them for examples of different speed limits in the local area, and to suggest why there are different limits in different places. Elicit the idea that the faster a car is going, the longer it takes to stop. Discuss what measurements are needed to work out a speed.

3: Match the speedsWorksheet 7Ke(2) provides a set of cards with descriptions of moving objects, and their speeds given in three different units. Ask pupils to cut out the cards and match them up. This activity is intended to familiarise pupils with the three common units for measuring speed, and to give them a feel for how speeds in the three different units compare. At its simplest they could just match up the speeds in different units by putting the cards for each unit into rank order.

Exploring tasks

1: Stopping distances (AT)Worksheet 7Ke(3) looks in more detail at the stopping distances given in the Highway Code. One of the questions asks pupils to plot a graph, including a line of best fi t. Some pupils may fi nd Skills Sheet 29 useful.

• The AT spreadsheet link on page 160 opens Stopping distances – a spreadsheet that includes the data on Worksheet 7Ke(3), plus information about stopping distances at night. This spreadsheet can be used for the graph plotting in question 4 on the worksheet. It also asks pupils to plot further graphs to compare thinking and braking distances during the day and at night.

2: Road safety postersFollow up the work on stopping distances in the Pupil’s Book and in Exploring 1 by asking pupils to design road safety posters or presentations, aimed at encouraging drivers to stick to speed limits.

Continue this theme by discussing any traffi c calming attempted in the local area. Using a large scale map of the local area, mark busy junctions, crossings, and any places where traffi c calming measures have been taken. If it is possible to take small groups out of school, perhaps in a minibus, this could be made into a survey. If not, pupils could contribute from memory or be asked to note any features they encounter on their normal route home.

ResourcesSugar paper; coloured pencils; plain paper; glue; large-scale map of local area.

Topic task plannerUse these tasks to adapt the exemplar topic plans to your own needs. Many tasks can be adapted to become different types (e.g. ‘starter’ rather than ‘exploring’). AT or AB/AT at the top of a task means that the task depends on using the ActiveBook and/or ActiveTeach; where these symbols appear in brackets it indicates that the task can be carried out with or without their use. Also consider using one of the plenaries from the previous topic as a starter task in this topic.


Starter 1 M/S 4–6 Classwork 1, 2 PLTS (Rl) 1b

Starter 2 M/S 4–5 Classwork 1, 2 1b

Starter 3 M 4 Classwork 2 1b c

Exploring 1 S 4–6 Classwork 1–4 ICT (SS), Num (L) 2a 1a, 2a 1b c

Exploring 2 M/S 4–5 Classwork 1, 4 ICT (PS) 2a 3a 1b c

Explaining 1 M/S 4–6 Classwork 1–4 2a 1b c

Explaining 2 M/S 4–6 Classwork 4, previous topics Num (L) 1b c

Explaining 3 M/S 4–5 Classwork 5 Lit (DS), PLTS (Ep) 2a, 2b 1b 1b c

Plenary 1 S 4–5 Classwork 3 ICT (SS) 1b

Plenary 2 M 4 Classwork all topics Lit (WF) 1b

Plenary 3 M/S 3–5 Classwork all topics PLTS (Rl) 1b

Plenary 4 M/S 3–5 Classwork all topics PLTS (Rl) 1b

Plenary 5 S 3–5 Classwork all topics PLTS (Rl) 1b


Plenary 7 M/S 3–7 Classwork all topics 1b

Plenary 8 M/S 4–7 Classwork whole unit PLTS (Rl, Sm)

Homework 1 M Homework 1, 2 previous topics 1b

Homework 2 S 6 Homework 3 Num (L) 1b c

Homework 3 C 6 Homework 5 Num (C) 1b

7Ke The need for speed

7Ke

UNIT12.indd 282 12/3/08 15:07:49


Explaining tasks

1: Pupil’s Book pages 160–161 (AT)This looks at speed and how the speed of a car affects the distance it will take to stop. The theme of journeys is continued by introducing distance–time graphs. Worksheet 7Ke(1) is the Access Sheet.

• Must: read through the pages with pupils and discuss the questions with them.

• The fi rst AT animation link on page 161 opens Distance–time graph – an animation showing how distance–time graphs can be used to show what happens during a journey.

• The second AT animation link on page 161 opens Acceleration – this shows how a distance–time graph is built up for a vehicle that speeds up and slows down.

2: Unbalanced forces and speedLink the work on speed to the earlier topics in this unit by discussing the role of unbalanced forces in changing speed, and the effects of friction, air and water resistance. Show pupils the stopping distances for cars quoted in the Highway Code (reproduced in the Pupil’s Book), and discuss the fact that these distances depend on a dry road and an alert driver. Pupils could also be asked to plot a graph of stopping distance against speed and describe the trend shown.

3: Pupil’s Book page 162 (AT)This looks at standards for equipment and training, and asks pupils to discuss whether or not they think such standards are necessary. There are also questions which help to revise some of the earlier content in the unit.

• The AT video link on page 162 opens Safety standards – a video showing Jim talking about how they know the equipment they use will do what it is supposed to, and why this is important.

Plenaries

1: Distance–time graphs AB/ATAfl The AT spreadsheet link on page 161 opens Distance–time

graphs – a spreadsheet with two distance–time graphs and sets of statements, for pupils to match the statements to the relevant parts of each graph.

2: Quick CheckAfl The Quick Check sheet provides a word puzzle to help pupils

to revise key vocabulary from the whole unit.

3: Quick Quiz revisitedAfl Revisit the 7K Quick Quiz to test pupils’ knowledge of the

content of this unit. If you have the ASP on CD-ROM use Quick Quiz 2 which provides the same activity but with the answers arranged in a different order. Pupils could fi ll in their answers on the 7K Quick Quiz Answer Sheet. Encourage pupils to identify for themselves areas where their understanding is still weak and decide how they are going to remedy this.

4: Ideas about forces ATAfl The third AT presentation link on page 161 opens Ideas about

forces – a concept cartoon with different statements about forces, some of which are incorrect. If this was used in Topic 7Ka Starter 3, ask pupils to look at the answers or comments they wrote at the time and note any changes they think should be made now they have learnt more about forces. If this has not been used before, ask pupils to discuss each statement and decide whether or not it is correct. If they think a statement is not correct, ask them to explain why they think this.

5: Designing sports equipmentAfl Ask pupils to imagine they work for a company that designs

and makes sports equipment. Some of the managers have asked why the company needs to employ scientists to help to design new equipment. Pupils will have to give a presentation to the management to persuade them that an understanding of forces is necessary. Ask them to prepare a set of notes or a list of things they would talk about if they had to give such a presentation. This activity can be done as an assessed task. A sheet of level descriptions is provided on page 284 of the ASP.



7: End of Unit TestAfl Use the 7K End of Unit Test. A mark scheme is given in the

ASP. Encourage pupils to identify areas that are still weak and to formulate plans to strengthen those areas.

8: Level ladderAfl Pupils should tick the boxes on the Level Ladder to record

those statements that they feel they know. Alternatively they can use a traffi c light system or the CRI index (see Introduction, page 17) to record degrees of certainty. Ideally pupils should be certain of all statements at a level to be sure they are working at that level. Encourage pupils to plan how to do further work on the things about which they remain unsure.

Homework tasks

1: Worksheet 7Ke(4) provides questions about speed and also revises some work on forces from earlier in the unit.

2: Worksheet 7Ke(5) asks pupils to interpret a distance–time graph of a bungee jump (where distance is presented as height).

3: Worksheet 7Ke(6) looks at running records in athletics and how they are measured.

The need for speed 7Ke

7Ke

UNIT12.indd 283 12/3/08 15:07:50

7k forces and their effects - pearson schools and fe ... · pdf filethis unit revises the...

Documents