I want to know the effect of different colors of light on plant growth. I think white light makes plants grow best. I buy 5 similar ferns of the same species, age, and height. I place one in white light, one in blue light, one in green light, one in red light, and one in a closet. All receive Miracle-Grow and are given 20 ml water once a day for 2 weeks. What could be the controlled variables, and what types of measurements can I make on the plants to determine how they did in different types of light?
You have done a really nice job so far of setting up a controlled experiment. I do not know your initial hypothesis, but I presume that it basically says, "if plants are grown in different colors of light, the plants will grown differently." You could have the complete opposite as the hypothesis too. "Plants will grow the same no matter what color light they are exposed to."
A goal of any "good" experiment is to control as many variables as possible. Controls are things that you want to remain the same from trial to...
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