To test the hypothesis, the experiment needs to include two groups: a control group of plants that received a set amount of light (four hours) and an experimental group that received different amounts of light (some eight hours, others twelve hours). All other variables such as amount of water, temperature, soil type, humidity, and nutrients would be kept the same. Then measure the amount of plant growth (plant height) in both the control group and the experimental group after seven days. Compare the growth in the control group with the amount of growth observed in the experimental group to determine which group showed more growth.
