Question

In an experiment to find out whether sugar dissolves faster in hot water than in cold water, what should be measured?

Rohan wants to test: Does the type of surface affect how far a toy car rolls down a ramp? Which of these should he not keep the same?

Assertion (A): In a fair test, only one variable is changed at a time. Reason (R): If several variables are changed together, we cannot tell which one caused the result.

In a fair test, the variable that we measure to see the effect is called the controlled variable.