Question

A student wants to answer the question “Does adding calcium powder to soil make pea plants grow faster?” She adds calcium powder to the soil of 12 plants and does not add it to the soil of a second group of 12 plants. She measures the growth of all of the plants in each group for a month. Which statement best summarizes the factors that need to be controlled in this experiment?

Answer 1

All plants should be the same age and health and be given equal amounts of water and sunlight.

Answer 2

All plants should be the same age and health and be given equal amounts of water and sunlight.