One of the key ingredients to most Science Fair Projects is the experiment. The experiment is what tests your hypothesis. Your goal will be to create an experiment that allows you to test different variable on the same situation. It would be difficult to explain this process without an example, so we will create an experiment to use throughout the entire article. Our experiment will involve testing plant grow with various fertilizers.
The first thing that we must establish is that a control is necessary. A control is simply one subject (plant in our case) that will not be exposed to any variables. Let say that we want to compare plant growth using these fertilizers: Brand A, Brand B, soil from a compost pile, and soil with manure. We have one variable, the fertilizer, and four test options. The control will be a fifth plant that has no fertilizer added to the soil. The control will give us an idea of the plant growth without the applied variable to compare to. For example, if three of our four plants do very poorly and our variable does not, then it is likely that it was the variable applied to those three samples that caused the poor growth. However, if we have the same situation and the control also does poorly, then there is a greater possibility that there was something else (other than the variable) that caused the poor growth. Examples might include a bad batch of plants from the start or that the plants became contaminated before or during the experiment.
Another factor that will guarantee better results is multiplying your test subjects. In the experiment listed above, we will have five plants (four variables & one control). If you created multiple sets, let’s say three, of the five plants, then we will gain better results. With multiple sets, we will be more likely to rule out if one subject did w
The key in every experiment is to set it up so that only one variable is changed among the subjects and that all other remain the same for each. In our example of testing fertilizer, we want to make sure that the type of soil, the amount of sunlight, the amount of water and the temperature are all the same very every subject. Not doing so could throw off your results by having multiple variable affecting the growth of the plants. Then you would not know which variable was the cause of growth (or lack of).
As your experiment progresses, you will want to keep accurate records. In our example for plant growth with fertilizers, you will want to check the plant height, width, color and other features on a regular basis. It would be best to use the same measuring tool each time, measure on a regular schedule (everyday, every other day, etc) and measure at the same time every time. Measuring at different times throughout the day may give incorrect readings because of how much sun light is getting to plant. Remember that the key is to make sure that everything is as similar as possible with all subjects except for the one variable that you want to change, the one you are testing.
