A group of your classmates want to see if fertilizer improves plant growth. They set up the following experiment: They planted three different types of plant seeds in three different types of soil. They placed all the planted seeds in either a dark or a light environment. Each plant was given the same amount of fertilizer. In a complete sentence, explain whether or not you think this is a good scientific design. What are two things that you could suggest for them to change in order to improve their experiment?