You are doing a science experiment for class, testing the effect of darkness on plants. Design a controlled ex

Question

You are doing a science experiment for class, testing the effect of darkness on plants. Design a controlled experiment to test the hypothesis that plants in the dark will grow more slowly than normal plants

Answer 1

Take six plants and divide them in to two groups "light" and "dark".  The "light" groups will receive 12 hours of light a day while the "dark" groups will receive no light.  Measure the height of each plant every day for one week.  After that week you can swap the groups so that the "light" group receives no light and the "dark" groups gets 12 hours of light a day.  Measure the height of each plant every day for one week.