Designing an Experiment Variables – The conditions of an experiment that can be changed, or have a number of different values. Independent Variables – The conditions or factors that the experimenter chooses for the experiment. Dependent Variables – The factors observed to undergo a change during the experiment. Note: the dependent variables depend on the independent variables. Determine the independent and dependent variables in the following experiments: 1. 2. 3. 4. 5. The amount of sunlight provided and plant growth The type of mouthwash and the amount of bacteria killed Mark received on a science test and the length of study time The amount of heat used and the amount of time it takes to melt a substance Sweetness of a cup of tea and the amount of sugar added Independent Dependent Controlled Experiments – in controlled experiments only one of the independent variables is changed, and the rest are kept constant. This is done to determine which independent variables result in the change of the dependent variable.