Question

the passage below describes an experiment.
germinating plants in a potting tray
josh wanted to grow cucumbers from seeds. he read that using a heating pad to heat up soil could help seeds germinate, or sprout, faster. josh prepared three potting trays, each made up of ten small pots of soil. he planted one cucumber seed in each small pot. then he placed one electric heating pad under each tray. he kept one of the heating pads turned off. he turned one of the heating pads up to 78°f and the other heating pad up to 88°f. josh observed how long it took for the seed in each pot to germinate.
in this experiment, the pots on a heating pad that was turned off were part of ____
a control group
an experimental group

Explanation:

In scientific experiments, a control group is a set of subjects or samples that are not exposed to the variable being tested, used as a baseline to compare against experimental groups. Here, the turned-off heating pad means this group is not exposed to the test variable (increased soil temperature), so it serves as the control.

Answer:

a control group