For a science class project, sandy wants to test the effect of rap music on pea plant growth. she plays loud rap music 24 hours a day to a series of pea plants grown under light and watered daily. at the end of her experiment, she concludes that rap is conducive to plant growth. sandy receives a low grade on this experiment from her teacher.
why did sandy’s teacher give a low grade for this experiment? what was the key problem with it? how could sandy change her experiment to fix the problem? rewrite the experiment so it will receive a better grade.

Sandy's teacher give her a low grade because it was not an experiment.

The key problem was that Sandy did not had a control group.

The new experiment will have two groups (control and experimental). Each group will have the same amount of pea plants, and the pea plants will be watered with the same amount of water at the same time daily. Also, pea plants will receive the same amount of light. The only thing that will change between groups will be rap music. In the control group, there will no music played while loud rap music will be played 24 hrs a day in the experimental group. At the end of the experiment, all pea plants will be measured, and the measures will be compared between both groups.

Explanation:

Experimental investigations are performed to evaluate the effect of a specific variable. In order to measure this effect, you have to control other variables. In the experimental design, you need to have more than one group, but at least two (control and an experimental). The control group is the group from which you will compare, so it will not be exposed to the independent variable. The experimental group is the one that has to be exposed to the independent variable.

In this case, the independent variable is rap music, and the dependent variable is the amount of growth.

the correct answer is:

a population changes in response to a change in the environment.

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