Answer
When experimental conditions are controlled, all physical conditions, except for one, are identical for all groups tested.The most important tasks is the prior to conducting an experiment is to eliminate all variables that you can not control in an experiment.
Work Step by Step
During experiments, researchers aim to study a single variable. By keeping the experimental and control group conditions the same, aside from the variable they are studying, they are assured that the outcomes that they find are due to the differences in the manipulated variable.