They place three thermometers in the sunlight and cover each of them with a sheet of paper (one black, one white and one with cellophane). They leave the sheets of paper in the same area, each with the same amount of sunlight for exactly 20 minutes. At the end of the experiment, they check the thermometer readings to see which sheet of paper is the “hottest” and which is the “coolest.” 3a. Identify the “independent variable” in this experiment.