Key Info

The design process involves multiple loops and circles around your final solution. You will likely test your solution—find problems and make changes—test your new solution—find new problems and make changes—and so on, before settling on a final design.

At this point, you have created prototypes of your alternative solutions, tested those prototypes, and chosen your final design. So you're probably thinking that your project is finished! But in fact, you have yet to complete the final and most important phase of the engineering design process—test and redesign.

Test and redesign requires you to go out and test your final design with your users. Based on their feedback and their interaction with your solution, you will redesign your solution to make it better. Repeat this process of testing, determining issues, fixing the issues, and then retesting multiple times until your solution is as successful as possible. Keep in mind that minor changes this late in the design process could make or break your solution, so be sure to be thorough in your testing!

User Test

The first step in user testing is to get in contact with the users of your solution. Go back to your problem statement, and remember your potential users. You will want to test your solution on this group of people. For example, if you are designing a website for kindergarten students, you will want to test your final solution with kindergarteners.

When it comes to testing, there is no such thing as too many testers! The more people that you are able to test with the more you will find out. So try to find as many users as you can who are willing to help you. A good goal to reach for is three to five users for each round of testing.

The second step, after you have located three to five users, is to present your solution to these users while the users are in the problem environment. The problem environment is the situation or atmosphere in which the problem you are trying to solve happens.

  • If your solution is a product, give the product to the users in the environment where they would use it. For example, if you designed a pair of sunglasses, you would give your sunglasses to the users outside while the weather is sunny. You wouldn't ask them to try the sunglasses at night or indoors, because those aren't situations where they would be using sunglasses.
  • If your solution is a website or software product, ask users to test it on computers. You wouldn't want to just show them pictures or explain the website, because how they interact with the computer itself is also important.
  • If your solution is an environment or experience, place your user in that environment or experience, and see how they react. For example, if you designed an after-school program for students, invite users to attend this program or a mock version of it. However, in many cases, having your users actually visit your designed environment or go through your designed experience will not be possible. An example is a student who designed a new school bus but obviously does not have an actual bus to use for testing. In a case like this, use a storyboard to present your solution to the users.

The third and final step of user testing is observing the interaction between the user and your solution. Record your observations in your design notebook. Watch closely as people use your product, navigate your website, or go through your designed environment or experience. Listen to what they say, but also watch what they do, see how they react, note where or when they get confused, and write down everything that happens during their interaction with the solution. Below are three questions to ask during testing. The answers will be helpful when you move onto the redesign phase of test and redesign.

  1. Are your users able to overcome the problem by using or interacting with your solution?
    • If yes, why are they successful?
    • If no, what problems do they encounter that prevent them from being successful?
  2. Do the users ever need to ask you any questions when using or interacting with your solution?
    • If yes, what questions do they ask? During what part of their interaction do they ask these questions?
  3. Do the users interact with your solution exactly the way that you intended for them to?
    • If no, what do they do differently?
  4. If you have measurable targets for your solution, did you meet them?


After you have tested your design, you will use your findings to complete a redesign of your solution. Use the findings from testing to:

  • Fix any problems that occurred, and
  • Further polish aspects of the design that were even more successful than you originally thought.

To make these changes, look at the answers to the three major questions you asked during testing:

  1. Is your user able to overcome the problem by using or interacting with your solution?

    If the answer is "yes," focus on why the user was successful. What specific aspects of your design helped the user to achieve success? Should those aspects become larger parts of your design? Should you make these features more prominent or more obvious to the user? Consider emphasizing these aspects of your design. Then, in the next round of testing, see if the user is able to achieve success even more quickly and easily.

    If the answer is "no," focus on the problems that users encountered during testing. What prevented them from achieving success? What changes to your design would eliminate these issues? Make these changes.

  2. Does the user ever need to ask you any questions when using or interacting with your solution?

    If the answer is "yes," focus on the questions that the users asked you. Why did they need to ask you a question? Were they confused? What part of the solution wasn't self-explanatory? You normally wouldn't be there to answer questions, so how can you make sure that the next users won't need to ask the same questions? Make changes that will eliminate these questions.

  3. Does the user interact with your solution exactly the way that you intended for them to?

    If the answer is "no," focus on what the users did that you hadn't intended to happen. Did their unexpected actions make your design more successful or less successful? If less successful, what changes could you make to your design to prevent these unexpected actions? What issues are causing the users to interact differently than intended, and how can you fix those issues? Make these changes.

  4. If you have measurable targets for your solution, did you meet them?

    If your design requirements call for your solution to be better, faster, or cheaper, you should measure the improvement that you made. If you met your targets, great! If not, how can you redesign your solution to improve its performance?

Once you have made changes to your design, go back and test again with your users. See if the improvements and changes you made negatively or positively affected your solution. Ask yourself the same three questions again, and then repeat the redesign again. Repeat this test and redesign process as many times as necessary to make your final solution as successful as possible. It may seem like you are doing the same thing over and over again, but with each test and redesign, you are greatly improving your project!

Free science fair projects.