Think about your favorite recipe, one you make the exact same way every time. Perhaps the recipe is for chocolate chip cookies, or banana bread, or apple pie. Now imagine you are partway through the recipe and realize you are missing one key ingredient, for example, milk or sugar. What would you do?
I would find the best substitute and proceed (so, yes, I have made bread without yeast and cake without eggs, neither of which I would recommend, but that is not the point here). The outcome (whatever you made) is usually different from the original version, but whether it is better or worse, any differences in the new version are credited/blamed on the one change made in the recipe.
Believe it or not, simple science experiments are not much different.
Let’s look at the analogy further with cookies:
• Materials = List of Ingredients
• Procedure = Recipe Instructions
• Question = What will happen if I use ____ instead?
• Hypothesis = Whatever you thought would happen when you made the substitution and why (note teachers and judges like to see the reasoning behind your predictions)
• Independent variable = New ingredient. For example, if you used soda instead of milk
• Dependent variable = Measureable differences in new version. For example, noticeable differences in taste, texture, color, size, viscosity, smell, shelf-life, etc.
• Control trial = original outcome (i.e. the traditional version of cookies)
• Experimental trial = new outcome (i.e. cookies made with soda instead of milk)
Simple experiments change one thing and look for a measureable change in another thing. The fancy word for those “things” is “variables”. Ready? See my advice on strategies for finding a creative idea.