Energy

Energy - Objectives What do students study in KS3? Where have

they come from? What is energy? In

Physics/Biology/Chemistry What ideas do pupils have about energy? Where could we start in Year 7? Which teaching models could we use? How could we approach teaching energy

resources?

Energy in the National Curriculum KS33 Range and content

This section outlines the breadth of the subject on which teacher should

draw when teaching the key concepts and key processes.

The study of science should include:

3.1Energy, electricity and forces

a. energy can be transferred usefully, stored, or dissipated, but cannot

be created or destroyed

b. forces are interactions between objects and can affect their shape and motion

c. electric current in circuits can produce a variety of effects.

Explanatory note: Energy: This includes the properties and behaviour of light and sound, renewable energy resources and emerging technologies such as fuel cells.

Energy in Physics KS3/4

Sound, light and waves

Electricity and magnetism

Prior teaching related to energy

Pupils have learned some material in Key Stage 2 science that underpins Key Stage 3

Look at the handout – suggest how each of the Key Stage 2 objectives is related to the teaching of energy in Key Stage 3

What is energy?

Look at cards on your desk

As a group decide whether you agree/disagree with each statement, or you are not sure

Try to come to a consensus

The Physicist’s View

Energy is conserved Energy spreads out spontaneously and is

less useable Energy can be stored and transferred The deliberate transfer of energy from one

location to another is what the physicist calls work

Energy does ‘NOT’ make things go.

Energy - Common Misconceptions

Energy is a substance– Whereas in reality - energy is an abstraction – may have some

basis in the ’caloric’ theory Energy makes things go

– No - Forces make things start moving. Energy exists in many different forms

– There are only really two forms of energy» Kinetic Energy» Potential Energy

Energy comes from fuels– The ‘chemical energy of a lump of a coal’ is a property of the

whole system - the fuel and the oxygen Heat is a form of energy

– It has been argued that we should not use ‘heat’ as a noun, but talk about ‘heating’ as a process

Light

Carbon dioxide + water + salts

Carbohydrate in Plants

Carbohydrate in

Animals

Oxygen + Glucose

Movement Biosynthesis Biotransport Bioluminescence Sound/electrical

Carbon dioxide + water Heat

Biologist's View

The Chemist’s View

C + 4H + 4O(g) (g) (g)

CH + 2O4(g) 2(g)

CO + 2H O2(g) 2 (g)

BOND BREAKING

ENERGY SUPPLIEDBOND MAKING

ENERGYRELEASED

Carbon, oxygen and hydrogen atoms

methane + oxygen

carbon dioxide + water vapour

Identifying children’s alternative conceptions: Concept Cartoons Look at the concept cartoon What is the misconception it illustrates? Could this be investigated using a practical

investigation? What would pupils do? If not, how else could you approach teaching

this?

Why concept cartoons work

They help make learners’ ideas explicit They challenge and develop learners’ ideas They apply scientific ideas in everyday

situations They promote discussion For more able pupils they can provide

cognitive conflict which helps to clarify ideas They help legitimise alternative viewpoints –

reduce the threat of giving the ‘wrong’ answer

Children’s Conceptualisation of Energy Vitamins give you energy Fit people have a lot of energy I did not have any energy left after doing cross country Energy is power My dog has a lot of energy, he runs around all the time Energy is like a force We cannot live without energy I am out of energy Everything has energy to make it go Sugar is a food which gives you energy When I go for a run, I use up all my energy Electricity can give you energy.

Some misconceptions

Energy is a fluid or ingredient Energy is used up Energy is fuel Energy makes things happen

A starting point in Year 7

It is suggested that we should move from familiar contexts to the less familiar

Hence a possible teaching sequence is

Energy in food

Energy in fuel

Electricity from fossil fuels/alternative resources

The energy content of food

Look at the labels on handout 2.9 Burn each of the four types of food Match the label to the food Explain your choice – which piece of

information on the label helped you decide? How could this be extended into an

investigation? How could you collect valid and reliable

data?

Comparing the energy content of different foods

Use the food labels provided Look at the energy content per 100 g of the foods Attach the labels to the washing line in a way that

enables you to compare the amount of energy stored in each

Now look at the mystery foods and discuss in your group where you think these foods belong

When you have made up your mind about the mystery foods, collect an answer sheet from your tutor

What would you need to think about if running this activity with Year 7 classes? Management/learning

An introduction to energy conservation as an accounting system Look at handout 2.13, page 1, and answer

the questions on page 2

Loop card game

Lunch

What is energy?

‘ … there is a certain quantity, which we call energy, that does not change in all the manifold changes which nature undergoes. That is a most abstract idea, because it is a mathematical principle: it says that there is a numerical quantity, which does not change when something happens. It is not a description of a mechanism, or anything concrete: it is just a strange fact that we can calculate some number and when we finish watching nature go through her tricks and calculate that number again it is the same.’ Richard Feynman

Dennis the Menace (adapted from Richard Feynman)

Imagine a child, perhaps “Dennis the Menace” who has blocks which are absolutely indestructible, and cannot be divided into pieces. Each is the same as the other. Let us suppose that he has 28 blocks. His mother puts him with his 28 blocks into a room at the beginning of the day. At the end of the day, being curious, she counts the blocks very carefully, and discovers a phenomenal law- no matter what he does with the blocks, there are always 28 remaining! This continues for a number of days until one day there are only 27 blocks, but a little investigating shows that there is one under the rug - she must look everywhere to be sure that the number of blocks has not changed. One day, the number appears to change - there are only 26 blocks. Careful investigation reveals that the window was open, and upon looking outside, the other two blocks are found.....

Different models for teaching energy

Look at the pictures Choose which description A, B or C most

closely matches what you would say to pupils

Record it on the handout 3.4 ‘Task H Response sheet’

The model you chose

Mainly A = transformation model Mainly B = transfer model Mainly C = hybrid

Energy transformation

Heat Light Sound Nuclear Kinetic Potential

– Gravitational– Elastic– Chemical

Electrical

Describe a bungee jump using the transformationmodel

Describe a bungee jump using the transformationmodel

Difficulties with the transformation model:

Gives the impression that energy must be transformed when work is done;

Plethora of terms does nothing to improve conceptual understanding – clutter;

Causes confusion about what is a process by which energy is transferred and what is a type of energy

What do physicists want students to know?

Potential energy and kinetic energy are sufficient to describe everyday situations

Mechanical working, heating and electrical working are three processes by which energy is transferred:

Energy transferred mechanically is W = Fd

Energy transferred thermally is W = mcT

Energy transferred electrically is W = QV

The ‘energy transfer’ model

In this model the energy is located in one place, and when something happens energy is transferred from that place to another by a process.

Typical use of language: ‘The energy in the battery is transferred to the bulb by

electricity and then from the bulb to the surroundings by light. Some energy is transferred to the surroundings by heating.’

‘Energy from the Sun is transferred to the leaf cells by light.’

‘Energy is transferred from the reacting chemicals to the surroundings by heating and light.’

‘A weightlifter transfers energy from his muscles to the bar by lifting (moving) his arms.’

Energy transfers in an electric torch

electric current light

heating heatingCell Filament bulb

Energy in surroundings

Energy in surroundings

Slide 5.8

A Sankey diagram showing energy transfers in an electric torch

Slide 5.9

Electric current

Heating

Heating

Light

Cell Bulb Surroundings

Surroundings

Using tokens with Sankey diagrams

Slide 5.10

Helping pupils to use the idea of energy conservation as an accounting system Choose one of the energy stories on handout

5.12 Use the squared paper and tokens supplied

to make a Sankey diagram representing the energy transfers in your chosen story

What would you need to think about if using this activity with children? Modifications/management/learning?

The usefulness of Sankey diagrams

How does using blocks or tokens with Sankey diagrams help pupils to understand:

Transfer of energy; Conservation of energy; Dissipation of energy; Energy efficiency?

What are the limitations of using Sankey diagrams in this way?

Energy Circus

At each station think about how you would describe what happens in terms of

a)The energy transformation model

b)The energy transfer model

What would you ask children to record? What do you need to think about when

organising a circus of experiments/stations?

Energy resources

Energy in the UK

The Energy Bill 2012 -2013 aims to close a number of coal

and nuclear power stations over the next two decades, to

reduce dependence on fossil fuels and has financial

incentives to reduce energy demand. Government climate

change targets are to produce 30% of electricity from

renewable sources by 2020, to cut greenhouse gas

emissions by 50% on 1990 levels by 2025 and by 80% on

1990 levels by 2050.

Task 1

Put the blue cards in rank order (or diamond)

An envoy visits another group to compare – discuss any differences

The envoy returns – do you want to make any changes?

Podcast: Today programme ‘Airline travel is not sacrosanct’ Listen to the podcast How might you use podcasts in the

classroom?

http://castroller.com/podcasts/BestOfToday/1220584

Task 2

Read the purple cards which describe ways of reducing CO2 emissions

Choose the option you think is the best Make a TV advert promoting it

Energy - Objectives What do students study in KS3? Where have

they come from? What is energy? In

Physics/Biology/Chemistry What ideas do pupils have about energy? Where could we start in Year 7? Which teaching models could we use? How could we approach teaching energy

resources?

Useful websites

www.sep.org.ukwww.iop.orgwww.ase.org.ukwww.standards.dfes.gov.uk/secondary

/keystage3/all/respub/sc_energy http://www.talkphysics.org/