1. Identifying Variables and Designing Investigations
How Science Works
28 August, 2019
Identifying Variables and Designing Investigations
This lesson should take approximately 50 minutes to 1 hour. Students should be allowed to work in pairs or small groups for the tasks.

2. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Learning outcomes:
By the end of the lesson you should be able to
Explain what the different types of variables are.
Recognise different variables in example experiments.
Understand why the consideration of variables is important when designing an experiment.

3. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
The INDEPENDENT VARIABLE
Also known as the INPUT variable.
This is the thing that you change or manipulate, the thing you are testing.
Students should copy the definition into the books so they have a record of it to refer to whenever needed.

4. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
The DEPENDENT VARIABLE
Also known as the OUTPUT variable.
This is the thing that you measure or observe, it’s the results of the experiment.
You expect the dependent variable to be affected by the independent variable.
Students should copy the definition into the books so they have a record of it to refer to whenever needed.

5. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
The CONTROL VARIABLES
Any variable that you keep the same in order to allow for a ‘fair test’.
Students should copy the definition into the books so they have a record of it to refer to whenever needed.

6. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Example No. 1
A student thinks that year 10 students will be better at doing a quiz than year 8 students.
Task 1: Write down the independent, dependent and control variables in this experiment.
Allow the students 3-5 minutes to discuss and write down their answers before moving on to the answers slide.

7. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Example No. 1
Independent variable = the year group the students are in (year 10 or year 8)
Dependent variable = the students scores on the quiz
Control variables = the same quiz should be used, students should have the same amount of time to complete it.

8. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Example No. 2
A student has made the following prediction for an experiment; “the more caffeine I drink the quicker my reaction times will be.”
Task 2: What are the independent, dependent and control variables in this experiment.
Allow the students 3-5 minutes to discuss and write down their answers before moving on to the answers slide.

9. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Example No. 2
Independent variable = the amount of caffeine drunk by the student (e.g. number of cups of cola)
Dependent variable = the students reaction times (e.g. how quick they can catch a ruler)
Control variables = the same type of drink, same method of measuring reaction time.

10. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Example No. 3
The light intensity was measured at different points moving away from the trunk of a large tree in full leaf.
Task 3: What are the independent, dependent and control variables in this experiment.
Allow the students 3-5 minutes to discuss and write down their answers before moving on to the answers slide.

11. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Example No. 3
Independent variable = the distance from the tree trunk.
Dependent variable = the light intensity.
Control variables = the same tree used for all measurements, the same light intensity meter, the same day/weather conditions.

12. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Example No. 4
Listening to music impairs your ability to study.
Task 4: What are the independent, dependent and control variables in this experiment.
Allow the students 3-5 minutes to discuss and write down their answers before moving on to the answers slide.

13. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Example No. 4
Independent variable = whether the student is listening to music or not.
Dependent variable = the students ability to recall information leant while listening to music (e.g. score on a memory test).
Control variables = the same type of music, the same information to be learnt.

14. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Designing an experiment.
The larger the surface area of a parachute, the slower the object will fall.
Task 5: design an experiment to test this hypothesis
Identify the variables – what are you going to change? How will you change it? What will you measure? How will you measure it? What needs to be kept the same to make the experiment a fair test?
Allow the students 5-7 minutes to discuss and write down their answers before moving on to the answers slide.

15. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Designing an experiment.
What is the optimum temperature needed for the enzyme amylase to work?
Task 6: design an experiment to test this hypothesis
What are the independent and dependent variables? How will you make it a fair test? How many different temperatures will you test? How will you measure the results?
Allow the students 5-7 minutes to discuss and write down their answers before moving on to the answers slide.

16. Identifying variables and Designing Investigations
28 August, 2019
Identifying variables and Designing Investigations
Plenary: Revisiting the learning outcomes
Show me, using a thumb up, down, or sideways, how well you think you have met each of the learning outcomes.
Explain what the different types of variables are.
Recognize different variables in example experiments.
understand why the consideration of variables is important when designing an experiment.
Traffic lights; red = I cannot carry out the learning outcome, orange = I could attempt the learning outcome but I am not confident in my ability, green = I could happily carry out the learning outcome.