The control group is the group that is unchanged, the group that you compare results with. The independent variable(s) is the quality that is changed in non-control groups. The dependent variable(s) is the quality that is affected by the independent variable. Usually, this is the quality you measure in an experiment. Example: You do an experiment that measures the effect of no sunlight on plant growth. You have 2 plants, one that will be grown in the dark and one grown in the sun. Since you are observing what NO sunlight will do, the control is the plant grown in the sun. That is the normal, unchanged group. The independent variable (the quality that is changed) will be the amount of sunlight that the plants are exposed to. The dependent variable could be the plant height, since that will be the quality you measure and it will be affected by the independent variable.