33. Crystal thinks that plants grow better with light than in the dark. To test this hypothesis,
she performed an experiment with the following steps:
• Plant five radish seeds in one cup of soil and five carrot seeds in another cup of soil.
• Give both cups the same amount of water.
. Place the radish seeds under a lamp, and water them every day.
• Place the carrot seeds in a dark closet, and water them every day
Crystal changed more than one variable in her experiment. Which of these changes should
Crystal make so that her data are helpful in answering her hypothesis?
a. Use only one type of seed
c. Place both cups in the closet
b. Place all the seeds in one cup
d. Use two different types of soil
Yes it is okay to use two different types of seeds for the experiment, but radishes and carrots are two different kinds of plants. She needs to have some radishes in the dark and light and some carrots in the dark and light.
