In a fair test, you should change only one variable so that you can see the effects of the variable you changed. Suppose you were investigating the flow rates of various liquids by measuring the time that each took to flow down a ramp.

What variable would you change during these tests?

What variables would you keep the same?

a) The variable that we will change will be the different liquids.

b) The variable which will be kept same will be the ramp angle, the time for measuring in each experiment and the heat.

Explanation:

In a scientific experiment, an independent variable is a variable which is changed by the researcher so that its effect on the dependent variable can be studied.

A dependent variable is a variable which is under study and might be influenced by changes in the independent variable.

It is best to study the effect of a single independent variable at a time so that we can easily infer the results.

In the scenario discussed in the question, we would change the different liquids so that the time taken by each liquid to flow down the ramp can be studied.

We will keep the ramp angle, the time (of each experiment) and heat for each of the experiments the same so that a just conclusion can be drawn.