ppt scientific method

So… How Do We Study

Science?

We use the Scientific

Method!!!

What is the Scientific Method?

• A logical, problem solving technique

• A Step-by-step way in which scientists answer questions.

Steps of the Scientific Method1. Observation 2. Ask a

Question3. Background

research

5. Design and conduct an experiment

6. Collect data

7. Analyze and Graph Data

8. Draw Conclusions

4. Formulate a hypothesis

STEP 1: Observation

• You observe something in the material world, using your senses or machines which are basically extensions of those senses.

AH—Look at this!

STEP 2: Ask a Question• The problem identifies what you want to find out.

State the problem in the form of a question:

• Examples: Ex. Do bean seeds grow faster when fed compost or fertilizer? How does __________ affect _______? What is the effect of _______ on ________? Why” and “What would happen if..” are also good beginnings of scientific questions.

• They must be testable: For example: Are Canaries prettier than blue

birds? Not testable

STEP 3: Background research

Scientists never start from scratch in putting together a plan for answering a question. You should use library and Internet research to help you find the best way to do things and insure that you don't repeat mistakes from the past.• Background research is necessary so that you know how to design

and understand your experiment and how to write a hypothesis. • Use a table with the "question words" (why, how, who, what, when,

where) to generate research questions from your keywords. For example:When does a plant grow the most, with fertilizer or compost?What plants are most suitable for my experiment?How many plants must I use?

• Plan to do background research on the history of similar experiments or inventions.

• Ask other people with more experience than yourself: your parents and teachers.

STEP 4: Formulate a Hypothesis

• A hypothesis is NOT just an educated guess about what you think will happen. It must be TESTABLE!!!!a) Answers the observation and predicts an

outcome of the experiment.b) “If… then… because” Statementc) If…..independent variable, then ….dependent variable

Ex. If given compost, then bean plants will grow faster than those given fertilizer

STEP 5: Design and conduct an experiment

• Experiment: a procedure to test the hypothesis• How are you going to test your hypothesis?• You Design an Experiment!• It must include: materials and a step by step

instructions• Must be run multiple times

Variables and Controls

• An experimenter changes one factor and observes or measures what happens

Control and experimental groups

CONTROL GROUP• The normal condition that you compare the

other conditions to• Group not exposed to variable being

testedused for comparison• Ex. Plant 1 is not given compost or fertilizer

EXPERIMENTAL GROUP• Group exposed to variable being tested• Ex. Plant 2 is given fertilizer and Plant 3

is given compost

Variables• A variable is something that can change,

either naturally or on purpose. In an experiment it is a factor that is different from one group to another.

• There are two types of variables: independent and dependant variables.

• The factor that is changed is known as the independent variable. The factor that the scientist has changed in order to test the hypothesis (on purpose). It is the cause

• The factor that is measured or observed is called the dependent variable. The result of what the scientist changed. It is the effect of what happened in the experiment.

Independent variable

The factor that the scientist has changed or manipulated in order to test the hypothesis (on purpose). It is the cause

Ex. Amount of Plant 1, Plant 2, Plant 3

Dependent variable• The result of what the scientist

changed. It is the effect of what happened in the experiment

• It is measured in the experiment• Changes because of the independent

variable• “Depends” on the independent variable

Ex. Plant growth

Constants or control variables

• They are what the scientist kept the same in both the control group and the experimental group

• Everything except the independent variable• Keeps the experiment ‘fair’• Ex: type of plant, type of soil…

Example of controls and variables

• For example, suppose you want to figure out the fastest route to walk home from school.

• You will try several different routes and time how long it takes you to get home by each one.

• Since you are only interested in finding a route that is fastest for you, you will do the walking yourself.

• Varying the route is the independent variable • The time it takes is the dependent variable

• Keeping the same walker throughout makes the walker a control variable.

STEP 6: Collect Data• Write all measurements and results of the

experiment. They may be quantitative (numbers) or qualitative

• Be consistent when you are checking your experiments and recording the results

• Use a table to organize your data in a chart with a title.– List your independent variable on the left side– Record your dependent variables on the right

side• If you have more than one dependent variable, use a

new column for each dependent variable

Example:

Step 7: Analyze and Graph data

• Make the data table into a graph• Graphs make it easier to see patterns in

the data. Graphs

X-axis independent variableY-axis dependent variable

Line graphLine Graph a. Used to show changes in dependent variable

(plant growth) over time.b. Must have title, x-axis title (with units) and y-

axis title (with units)c. Compare and look for trends and patterns using

graphs example

5 10 15 20 25 30 35 40 45 50 55

0

1

2

3

4

5

6

Growth of Plant A Over Time

Time (Days)

Pla

nt H

eigh

t (c

m)

Bar graphBar Graph a. Use it when a set of measurements can be split

into discrete and comparable groupsb. To show the relative change between these

groups.c. Must have titles and legend

0

1

2

3

4

5

6

Average Plant Growth over 50 Days

Plant A (Control)

Plant B (Fer-tilizer Added)

Plant C (Compost Added)

Plant A Plant B Plant C

Ave

rage G

row

th in

Centim

ete

rs

Pie chartPie Grapha. When showing parts of a whole..i.e.

percentagesb. Must have a title and a legend

• Indicate the results. Explain why those results where given.

• Answer:– Do your results/data support your hypothesis? Why or

why not? – What are ways you can improve your data? – What would you do differently if you were to repeat the

experiment?

Step 8: Draw conclusions

Step 8: Draw conclusionsClaima. Restate your hypothesisb. Ex. If given compost, then bean plants will grow taller than those given

fertilizer. Evidencec. Accept or reject your hypothesisd. Use the numbers from your chart and graph to explain why.e. Ex. Plant C which was given only compost grew to a maximum height of 5

cm, Plant B which was given fertilizer grew to a maximum height of 4cm and Plant A which was given nothing at all grew to a maximum height of 3cm. Therefore, the hypothesis is accepted.

Reasoningf. Scientifically explain WHY what happened occurred.g. Ex. Fertilizer contains only trace elements such as phosphorous,

nitrogen and sulphur while compost contains decaying matter which can provide many complex organic nutrients for a bean plant. Therefore, the plant treated with compost grows taller.

• A lab report MUST be written after every investigation.

• A lab report contains the following parts: 1. Title 2. Introduction 3. Materials 4. Procedure 5. Results 6. Conclusions

Comunicate Results: Lab Report