Step 3 Design Your Experiment

1. Write a general plan

Don't worry about the exact specifics here. Just focus on the big picture. In general what are you going to do? This step will help you to plan your time and get the project done. Here are some things to consider:
  • Where will you conduct this experiment? If not at school where are you going to put your experiment so that it doesn't bother anyone, you can assure it won't be disrupted by pets or babies, and it will be safe from changes in temperature or movement?
  • What will you actually be doing? For example, measuring something, timing something...
  • What are some potential problems you may encounter and how will you solve them?
  • What are the safety and environmental concerns?

2. Design your experiment

Be sure to check the experimental design page.
Your experiment needs to test your hypothesis. Stay focused here. It is easy to get too complicated at this point. If you refer to what you have done in the previous steps you will see that you almost have it. This is the step where you figure out exactly how you are going to do the experiment so that it tests the research question.

Consider this when you design

  • How will control and keep constant everything except the independent or manipulated variable?
  • How will you measure your dependent or responding variable?
  • Plan ahead by writing down all details of the materials and methods you will use.
What is the effect of light wavelengths on the biomass gained by basil plants?
In my experiment I will use three different types of light bulbs that give off different wavelengths of light. Under each type of light I will grow five basil plants, each in a separate container. The plants will start as sprouts no more than one centimeter high. I will grow the plants for three weeks. At the end of the experiment I will remove the plants from the soil, dry them in an oven and mass each plant on a balance. I can then find the average biomass in grams for plants from each light source to make comparisons. During the experiment, all plants will be watered and otherwise cared for equally.