Cattails A Scientist noticed that cattails grew only in swampy parts of his backyard. He decided to try to find out why. He went to the library and found out the following facts: Cattails are not found in deserts, Cattails are usually found in many swamps, Cattails sometimes grow in rivers and streams. The scientist thought for awhile, then said, " I think I have figured out the answer. Cattails need a lot of water to grow." He then went into his yard and dug up 100 cattails. He divided them into four groups. Each group contained 25 cattails. All of the groups were grown in the same type of soil, they all received the same amount of light, and they were all kept at the same temperature. There was only one difference between the groups. Group 1 received 4 mL of water a day. Group 2 received 3 mL of water a day. Group 3 received 2 mL of water a day. Group 4 received 1 mL of water each day. Every day he went out and measured the plants. After 30 days he observed that the plants in group 1 had grown an average of 8 cm. The plants in group 2 had grown an average of 4 cm. The plants in group 3 had grown an average of 2 cm. The plants in group 4 had grown an average of only 1 cm. He then decided that the amount of water that a cattail receives affects its growth. Plants that receive more water, grow more. The scientist then repeated his experiment using another 100 cattails

An experiment is a carefully controlled study which establishes a cause and effect relationship between variables. There must be a dependent variable and an independent variable.

The dependent variable in this case is the length of the cattails while the dependent variable is the volume of water received. The control group is the group that did not receive any water.

Learn more about experiment: https://brainly.com/question/9199868