This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
See first:
Part I: 3 Strategies for an Original Science Fair Project
Part II: How to Answer the 5 Most Common Questions from a Science Fair Judge
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Designing your own science fair project should be exciting and fun, but without a little guidance it is often stressful for parents and students. This post is to help both of you get started designing an original, creative, and technically correct science fair project. First, keep in mind the 5 basic steps of the scientific method (see Part I: 3 Strategies for an Original Science Fair Project).
QUESTION => HYPOTHESIS => EXPERIMENT => RESULTS => CONCLUSION
Sounds straightforward, but finding a good question is usually the biggest hurdle, so let’s take a look at the type of question you should be looking for. The structure of your question needs to be something like…
What is the effect of one thing on another thing?
What happens to something when I change something else?
If I increase this thing, what will happen to that thing?
The scientific term for those “things” is variables.
One variable will be changed by the student. That variable is called the independent (or manipulated) variable. In the questions above, the independent variables are “one thing”, “something else”, and “this thing” because these are the variables that will be manipulated.
Another variable in the experiment will be monitored to see if anything has happened to it in response to the changes in the first variable (i.e. the independent one). The variable that the student thinks might change is called the dependent (or response) variable. In the questions above, the dependent variables are “another thing”, “something”, and “that thing”. And the prediction for how it might change is called the hypothesis.
For example: How does the length of the straw affect the distance traveled by a spitball?
Here, the independent variable is the length of the straw and the dependent variable is the distance traveled by the spitball.
Everything else, such as type of straw, diameter of straw, type of paper used for spitball, amount of paper used for spitball, angle of straw, etc., is not part of this specific question, so the student will not focus on them (i.e. the student will keep these things the same when conducting their experiment). Sometimes we call these controlled variables, but that often confuses students because they are not the actual “control”. Other times we call them constant variables, but that is an oxymoron (how can something be both constant and variable?). Use whatever terminology the teacher asks for, but note that as long as they are not changed, they will not affect the results.
Getting from question to hypothesis is the next step. The choices for hypotheses, and it is really important that the student picks one BEFORE conducting the experiment, are:
As the length of the straw increases, the distance the spitball travels increases because …
As the length of the straw increases, the distance the spitball travels decreases because …
As the length of the straw increases, the distance the spitball travels does not change because …
All teachers and science fair judges like to see the reasoning behind why the hypothesis was chosen. The reasoning shows the student did research or has some understanding of, or interest in, the question.
Getting from question to experiment is now easier. The student will CHANGE the independent variable, and MEASURE the dependent variable. Repeat at least 3 times. Experiment done! Now graph your results, make a conclusion, and get ready for judging (see Part II: How to Answer the 5 Most Common Questions from a Science Fair Judge).
FYI: If you are interesting in the spitball experiment, you will need to find a way to standardize the “blowing” of the spitball. In other words, how will you make sure that the puff of air is the same each time? (Hint: what could you use – besides your own lungs – to provide the puff of air?).
Also, make it your own project by asking a slightly different question. Perhaps something like: How does the type of paper affect the stickiness of the spitball? Here you will need to figure out a way to quantify (i.e. generate a number) for “stickiness” (Hint: sticky objects will stick longer than not-so-sticky objects, and time is an example of a quantitative, dependent variable).
Good Luck! There is more science fair project help at my website, http://science-fair-coach.com