4. Experiment and test out your solution

Testing your solution is a huge part of your project. The method you choose should relate to your problem and solution, and also help you gather results that you’ll use in your conclusion.

This section will walk you through the different methods and challenge you to critically investigate your thinking and refine your solution.

“Doing is the best kind of thinking.”
Tom Chi, Co-Founder of Google X

How to conduct a fair test

Whether you’re testing with the scientific method, engineering method, or computational thinking, you will need to ensure that your test is fair. We do this by looking at our variables and by doing repeat tests.


In any experiment you have an independent variable and control variables. Control variables are the things that you keep constant, while the independent variable is what you change. You only change one independent variable at a time, so you can tell what effect it has.

Example: I want to measure how temperature affects a plant’s growth. My independent variable is temperature—the thing I’m measuring and will change throughout my test. My control variables are other things that I need for the plants to grow, e.g., amount of light, type of plant, amount of soil, and the amount of water they are given. I make sure I keep these constant while I change the temperature.

Repeat tests

To be able to draw conclusions, you need to have reliable, accurate data to base them on. Repeat tests enable you to see a pattern and give averages which are more reliable than taking a single reading.

Repeat tests help you spot and discard any anomalies in your data. An anomaly is something unexpected and not in line with what you are seeing with other results, e.g. all readings in an experiment are between 19 and 21, but there is one which is 32—this would be an anomaly.

Testing tips

You’ve followed the problem-solving steps, now it’s time to put all that thinking into action: carry out your test and get results.

  • You’ll need to read the official rules and pay special attention to the health and safety procedures.

  • Make notes along the way---if something doesn’t work, can you go back a few steps? What were your original ideas or questions? Maybe with the knowledge you now have, one of those could work better---or maybe you have new ones!

  • Keep communicating. Ask your friends, family, and teachers what they think. You may even want to reach out to an expert---try writing to an expert (that’s exactly what Shree Bose, the first Google Science Fair Grand Prize Winner, did!).

  • Find out more about Google Science Fair and key dates at on the Competition info page



Use cubing to refine all angles of your project.

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Fine tune your solution with a SCAMPER approach.

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