Question

suppose that you want to measure the effect of an oil spill on plant growth. for this purpose, you use three identical plants that you water daily for two weeks. one plant gets a tablespoon of engine oil added to its daily water and another gets two tablespoons of engine oil added to its daily water. the third plant is watered with plain water. you measure the height of all three plants after two weeks. what is the independent variable? what is the dependent variable? what is the test group? what is the control group?

Explanation:

1. Independent Variable

The independent variable is the factor that is manipulated in an experiment. Here, the amount of engine oil added to the water (0, 1, or 2 tablespoons) is what's changed to see its effect on plant growth.

The dependent variable is the factor that is measured and depends on the independent variable. In this experiment, plant height after two weeks is measured to see how it's affected by the oil, so it's the dependent variable.

Test groups are the groups exposed to the independent variable (the oil). The plants with 1 tablespoon and 2 tablespoons of engine oil in their water are the test groups as they receive the treatment (oil) being tested.

Answer:

The amount of engine oil added to the daily water (0, 1, or 2 tablespoons)

2. Dependent Variable