Emily wanted to see what battery lasted the longest. She put each battery into a clock and recorded the time that the clock stopped. She used Duracell, Energizer, Kroger bran, and EverReady. What is the control variable and the contstants?

A constant is something whose value cannot be changed and is used for comparison purpose.

Explanation:

The controlled variable is a type of variable whose value is kept constant during the experiment to get the desired or expected result. The difference between constant and a control variable is that the constant can never be changed.

However, the value of control variable can be changed but is kept constant with a purpose in an experiment to get the data. The controlled variable in a battery can be the multi meter that should be used for all the batteries.