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Planning an Investigation: Hypothesis and Method

In this worksheet, students practise planning a scientific investigation and forming a hypothesis. The topic used is Biology, but the skills apply to all other science disciplines.

'Planning an Investigation: Hypothesis and Method' worksheet

Key stage:  KS 4

Curriculum topic:  Working Scientifically: Experimental Skills and Strategies

Curriculum subtopic:  Applying Knowledge of Techniques, Apparatus and Materials

Difficulty level:  

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Worksheet Overview

QUESTION 1 of 10

Drugs affect the rate of our reactions depending on their properties. For example, depressants, like alcohol, slow us down. Therefore, drinking and driving is prohibited as well as driving after consuming more than the recommended amount of alcohol. Other drugs, like caffeine, are stimulants and make us alert. They are said to decrease our reaction time, which means when we have them, we react faster.

Athletes are tested prior to competitions. They are disqualified and not allowed to compete if they are found to have taken stimulants, because they have an advantage over other competitors.

 

You have to design an experiment to find out if stimulants decrease reaction times. The experiment must involve the time it takes to catch a ruler; this is how you will measure the reaction time.

 

 

I will now take you through a series of questions. Your answers will help you plan most of your experiment.

First, you have to form your hypothesis. This is a scientific word for 'prediction'. You must predict what you think your results will show. It is always advisable to do your research on the internet prior to forming a hypothesis, so you can see what other people have done on the topic. 

Using the scientific information about stimulants provided in the Intro, choose the correct option below as your hypothesis.

Caffeine will increase reaction time.

Caffeine will decrease reaction time.

Caffeine will not affect reaction time.

Having in mind the previous hypothesis, you must now think how you will test it. You will measure how long it takes for someone to catch a ruler before and after drinking a caffeine drink. Let's stick to cola.

What is your independent variable? What are you changing to measure the reaction time?

whether a specific individual has had a cola drink or not

how much cola a specific individual has had

the person having the cola drink

Your dependent variable is the one you are measuring.

What is your dependent variable in this investigation?

the amount of cola

the reaction time

the distance from the beginning of the ruler, where the person catches it

In every investigation there are control variables. These are factors that must remain unchanged throughout the experiment to ensure it is a fair test and the results are valid.

Click the main control variable in this investigation.

cola brand

person catching the ruler

person dropping the ruler

Suggest what other control variables you would choose. Four options could apply.

ruler

person dropping the ruler

the height the ruler is dropped from

distance of the person's fingers from the ruler before it is dropped

amount of cola drink

In experiments like this one, do you think it helps to inform the person catching the ruler of the true purpose of the experiment?

yes

no

For every investigation you are doing, you must list the equipment and resources you will need.

Tick four resources needed for this experiment.

ruler

measuring tape

cola drink

person catching the ruler

person dropping the ruler

In all experiments, it is essential that you ensure your results are reliable.

Tick the option that will enable you to do that.

identify the correct independent variable

repeat the test several times

use a stopwatch

Take a look at the picture below.


 

What is wrong with the way the boy is holding the ruler? Two answers apply.

He is holding it in the middle.

He is holding it upside down.

He is holding it straight.

He is not holding it straight.

Put the following sentences in order to provide the method of your experiment.

Column A

Column B

1
Person B should then drink a cola drink.
2
The distance from the beginning of the ruler to th...
3
Agree a signal that the ruler is dropped, for exam...
4
Do steps 2, 3, 4 and 5 again.
5
Person A must hold the ruler from a certain height...
6
Person B must wait with their fingers a certain di...
7
Steps 2, 3 and 4 must be repeated at least twice m...
  • Question 1

First, you have to form your hypothesis. This is a scientific word for 'prediction'. You must predict what you think your results will show. It is always advisable to do your research on the internet prior to forming a hypothesis, so you can see what other people have done on the topic. 

Using the scientific information about stimulants provided in the Intro, choose the correct option below as your hypothesis.

CORRECT ANSWER
Caffeine will decrease reaction time.
EDDIE SAYS
The scientifically correct option is the second one: Caffeine will decrease reaction time. This would be expected for all stimulants. We chose caffeine here, because you can easily test it using coffee or a cola drink, which contain caffeine.
However, the nature of science is such that you may also form any hypothesis. You may have some reasons to believe that caffeine will increase or not affect reaction time.
  • Question 2

Having in mind the previous hypothesis, you must now think how you will test it. You will measure how long it takes for someone to catch a ruler before and after drinking a caffeine drink. Let's stick to cola.

What is your independent variable? What are you changing to measure the reaction time?

CORRECT ANSWER
whether a specific individual has had a cola drink or not
EDDIE SAYS
In this experiment you are investigating how a specific individual's reaction time changes before and after drinking cola. So what you are changing is 'whether a specific individual has had a cola drink or not'. This is your independent variable.
  • Question 3

Your dependent variable is the one you are measuring.

What is your dependent variable in this investigation?

CORRECT ANSWER
the distance from the beginning of the ruler, where the person catches it
EDDIE SAYS
This question is tricky. You must have done a lot of research if you answered it correctly. In this experiment we must actually measure reaction time, but the most accurate way of doing this is by measuring the distance on the ruler where the person catches it. There is a conversion table that shows you what reaction time each distance converts to.
  • Question 4

In every investigation there are control variables. These are factors that must remain unchanged throughout the experiment to ensure it is a fair test and the results are valid.

Click the main control variable in this investigation.

CORRECT ANSWER
person catching the ruler
EDDIE SAYS
The person catching the ruler is the main control variable here. This person will perform first before having the cola drink and the same person must have the drink and do the test again. Otherwise, it is pointless comparing reaction times before and after the drink, as different people have different reaction times.
  • Question 5

Suggest what other control variables you would choose. Four options could apply.

CORRECT ANSWER
ruler
person dropping the ruler
the height the ruler is dropped from
distance of the person's fingers from the ruler before it is dropped
EDDIE SAYS
The first four options are correct. The last one should also be kept the same if different people are tested and their reaction times are compared. Additionally, different types of cola could be tested and the amount should also be kept the same then.
  • Question 6

In experiments like this one, do you think it helps to inform the person catching the ruler of the true purpose of the experiment?

CORRECT ANSWER
no
EDDIE SAYS
If you inform the person tested that you are measuring reaction time, they may be biased. This means they may put in extra effort when catching the ruler to prove their point. Usually, though, participants must be informed about the purpose of experiments, so they can happily agree to take part.
  • Question 7

For every investigation you are doing, you must list the equipment and resources you will need.

Tick four resources needed for this experiment.

CORRECT ANSWER
ruler
cola drink
person catching the ruler
person dropping the ruler
EDDIE SAYS
In order to do this experiment, you need a ruler, a cola drink, a person catching the ruler and a person dropping the ruler. The measuring tape is not necessary, as the distance is measured on the ruler itself.
  • Question 8

In all experiments, it is essential that you ensure your results are reliable.

Tick the option that will enable you to do that.

CORRECT ANSWER
repeat the test several times
EDDIE SAYS
Measurements must be repeated in scientific investigations at least three times. In this experiment, it is worth taking at least three measurements before drinking the cola and three after.
  • Question 9

Take a look at the picture below.


 

What is wrong with the way the boy is holding the ruler? Two answers apply.

CORRECT ANSWER
He is holding it in the middle.
He is not holding it straight.
EDDIE SAYS
The boy is holding the ruler in the middle and he is not holding it straight. This will not provide accurate readings, as the distance will not be measured correctly.
  • Question 10

Put the following sentences in order to provide the method of your experiment.

CORRECT ANSWER

Column A

Column B

1
Agree a signal that the ruler is ...
2
Person A must hold the ruler from...
3
Person B must wait with their fin...
4
The distance from the beginning o...
5
Steps 2, 3 and 4 must be repeated...
6
Person B should then drink a cola...
7
Do steps 2, 3, 4 and 5 again.
EDDIE SAYS
The correct order is:
  • Agree a signal that the ruler is dropped, for example, 1-2-3 Go!
  • Person A must hold the ruler from a certain height and drop it after the signal.
  • Person B must wait with their fingers a certain distance from the ruler and catch it as it drops.
  • The distance from the beginning of the ruler to the point that it was caught must be measured and noted down.
  • Steps 2, 3 and 4 must be repeated at least twice more.
  • Person B should then drink a cola drink.
  • Do steps 2, 3, 4 and 5 again.
  • ---- OR ----

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