Designing Your Experiment

Your investigation or scientific question should follow a logical, orderly method of solving your problem. Figure 1 (missing) shows a flow chart that Mr. Don Burnette uses with his classes to explain the process of investigating. First, you must develop a hypothesis, a possible solution to your problem. Library research will give you that important background information so that you can proceed in the proper direction. Using the work of others as a foundation for your work is the way progress is made in science. Looking at other's work should help you ask more specific questions, and finally clearly state a probable solution to your scientific problem.

For example, you may want to look at the effects of seaweed on plant growth. Many people on Cape Cod use seaweed in their gardens but how good is it? Since eelgrass is a common seaweed in this area we will use it. Your hypothesis might be that eelgrass will cause increased growth in the height of bean and corn plants.

Next, you must devise a logical, orderly way to test your hypothesis. No matter how sure you are of your probable solution, it cannot be accepted until it is tested many times. Occasionally the evidence you gather may show the need to make changes in your hypothesis, see Figure 1. So be open-minded, in science a hypothesis may be changed.

The testing that you devise is called an experiment. In order for your experiment to lead you to the solution of your problem it should test the effect of one thing on the outcome of the experiment. This one factor tested is called the experimental factor. The other major element of your experiment is the control group. This is used for comparison, and it's carried out in the exact manner as the experimental part. Observing the control highlights the results of the experimental factor. This experiment should be designed so that it may be repeatable by anyone, anywhere. Also, carefully list your methods and materials so that this repeatability can be achieved.

In our experiment with eelgrass, the experimental group would receive a specified amount of seaweed extract at specified times. The control group would exactly duplicate the experimental group in light, pot size, amount of water, etc.; only the seaweed would be left out. Each group would have the same number of plants in it and that number would be as large as manageable. Best results would be achieved if the plants were all taken as cuttings from the same plant or if they were all F1 hybrids grown from seeds.

Return to Science Fair Primer.