- A Fancy Word For Factors That Change!

Scientists have a special word for factors that can change in an experiment. They are called variables (from the word ‘vary’ meaning ‘to change’). Remember that when you do an experiment, only one variable should change.

This factor is called the test variable. It is the variable being tested. In the case of the eating competition, the test variable is the person eating.

Another type of variable is called the measured variable. This is what is being measured.

In the case of the eating competition, the measured variable is the time taken to eat the food. The measured variable will change because the test variable changes.

The other variables, the ones that stay the same, are called controlled variables. In the case of the eating competition, the control variables are the type of food eaten, the type of plate used, the location, the way the food is cut up, and so on.

o Michael and Nicole had a competition to decide who could read the fastest.

Below are the variables they used. Next to each one, indicate if it is the test,
measured or controlled variable/s.

The story to be read

The time taken to finish reading

The person reading

The room in which they read

The type of chair they sat on to read

o Mrs Floral did an experiment to test which type of plant grew the tallest.

Below are the variables she used. Next to each one, indicate if it is the test,
measured or controlled variable/s.

The amount of water each plant received

The amount of sunlight each plant received

The type of plant

The type of soil used

The height of the plants

The type of fertilizer used