Two students are planning an experiment that will test how planaria (aquatic flatworms) respond to different
environments. They will conduct two investigations--one that tests the worms' responses to different water
temperatures and one that tests the worms' responses to different levels of acidity. Student 1 wants to buy two
groups of flatworms and use a different group for each investigation. Student 2 thinks the same group of worms
should be used for both investigations.
Do you think either student's method would give more accurate results? Why or why not? Explain your response.