Section Assessment (pag.80)

SKILL ACTIVITY                                                                                                                                                                                         The dependent variable is dependent on the independent variable, and the independent variable is independent of the others. Control variables are controlled to make sure that the independent variable is the only factor causing a change in the dependent variable. Plant growth is likely affected by fertilizer (making it dependent), but fertilizer application is not affected by plant growth (making it independent). The amount of sunlight can affect growth rate, so it's controlled to stay the same in each experiment.                                                                                                                                                                             Let's look at a few different experiments to get a better idea of how these variables work. Say, for example, that you wanted to look deeper into that question you had earlier about fishing. The experiment you run depends entirely on the question you ask.

To start, you might ask, 'When is the best time of day to catch fish?' From past experiences, you hypothesize that fish are more active in the morning; therefore, this is the best time of day to catch fish. In your experiment, the time of day is the independent variable because this is what you change in the experiment. Dependent on this is the number of fish you catch, so this would be your dependent variable.

For this experiment, you will need to control for many factors, so you will have several different control variables. First, you need to make sure that you use the same equipment to catch fish each time. If you used different lures each time you went out, you would have no idea if the number of fish you caught was related to the time of day or the lure you used because both variables changed. This makes the fishing equipment one control variable.