Question

Robert wanted to find out what toothpaste made teeth the cleanest. Everyday he brushed his teeth with a different product and then took a plaque test to see how much plaque was left. He used Crest, Colgate, Close-up, and water. The fact that he used the same amount of each toothpaste would be an example of a (an)

10 points

Answer 1

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Answer 2

controlled variable

Step-by-step explanation:

the amount of toothpaste is kept the same throughout the experiment, controlled variable is the variable that is kept constant.