1. How Science works:
Variables

2. Learning Objectives
You should learn :
About the different types of variables,
How to identify them when doing your practical work.

3. Variables are things that vary and change

4. Variables In any experiment there are 3 variables:
some control variables
an independent variable
a dependent variable
Let’s look at each type….

5. Control variables
These are all the variables that must not change, to make sure it is a fair test.
Also called “constants”

6. Independent Variable This is the thing that you decide to change.
What is tested
What is manipulated

7. Dependent Variable This is the variable that changes as a result.
It is the variable that you measure.
What is observed
What is measured
The data collected during the investigation

8. Identify the independent, dependent, and control variables.
Example Situation
Students of different ages were given the same jigsaw puzzle to put together. They were timed to see how long it took to finish the puzzle.
Identify the independent, dependent, and control variables.

9. Control Variables
These are all the variables that must not change, to make sure it is a fair test.
Same puzzle
All of the participants were tested with the same puzzle
It would not have been a fair test if some had an easy 30 piece puzzle and some had a harder 500 piece puzzle.

10. Independent (input) variable
This is the thing that you decide to change.
The ages of the students
Different ages were tests by the scientists
You decide the ages to be tested, so:
The ages of the students is the independent variable.

11. Dependent (outcome) variable
This is the variable that changes as a result. It is the variable that you measure.
Which is the dependent variable here?
The time it took to put the puzzle together
The time was observed and measured by the scientist

12. Identify the independent, dependent, and control variables.
Another Example Situation
The higher the temperature of water, the faster an egg will boil.
Identify the independent, dependent, and control variables.

13. Variables
Controls: type of egg, stove, pots used
Independent: the temperature of the water
Dependent: time needed to cook the egg

14. Learning Outcomes
You should now:
Understand the difference between - independent, - dependent, and - control variables
Be able to identify these variables when doing your practical work.