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, "|
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.