What is the purpose of controlling the environment when testing a hypothesis?
1.it allows the scientist to determine the effect of the changed variable.
2.it allows samples and organisms to be tested under comfortable conditions.
3.it makes it easier for the scientist to perform the steps of the experiment.
4.it ensures that the scientist is undisturbed while performing the experiment.

1. It allows the scientist to determine the effect of the changed variable.

Let's say there was an experiment showing the effect of water on plant growth. The environment (in this case, the other variables including the amount of sunlight) would need to be kept under control in order for the results to be clear. If there was a different amount of sunlight during each trial, then the results would be effected by both the water and sunlight, making the results incorrect for the experiment.

When measuring an earthworm you would most likely have to go with centimeters