How Science works: Variables

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

Variables are things that vary and change

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

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

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

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

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.

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.

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.

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

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.

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

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.