8 · The engineering design process (build → test → iterate)

Here's the secret real engineers know: the first version is never the final version. Engineers don't expect to get it perfect on try one. Instead they follow a repeating cycle called the engineering design process. NASA's Jet Propulsion Laboratory — the team behind the Mars rovers — lays the steps out like this (NASA JPL Education, n.d.):

1. Identify the problem — what exactly are you trying to solve?
2. Brainstorm solutions — come up with lots of ideas, even silly ones.
3. Select a design — pick the most promising idea to try.
4. Build a model or prototype — make a quick, rough version. (A prototype is a first test version, not the finished thing.)
5. Test and evaluate — try it out and see what actually happens.
6. Share your solution if it works — or iterate if it doesn't.

That last word is the whole point. To iterate means to go back, improve, and try again. NASA JPL shows it as a flow chart that loops: if your test fails, you "cycle back" to building and testing — "building, testing, and evaluating until a solution is found" (NASA JPL Education, n.d.). Failure isn't the end of the process; it's a normal step in the process. Every failed test teaches you what to change next.

This is why engineers love prototypes made of cardboard, tape, and spare parts: a cheap prototype is fast to test and easy to change. You learn more from a rough version you actually test than from a perfect version that stays in your head.

IEEE — the world's largest organization of engineers — runs TryEngineering, a library of more than 130 free, hands-on engineering lessons built around exactly this "design, build, test, improve" loop, with clear goals and limits (called criteria and constraints) for each challenge (IEEE TryEngineering, n.d.).

Try this (household items). Pick a tiny problem — say, "a stand that holds my phone at a good angle." Run the whole cycle with only paper, cardboard, and tape: brainstorm, build a quick prototype, test it (does the phone actually stay up?), then iterate at least once to make it better. Notice how much your second version improves on the first.

Check yourself. What does it mean to iterate, and why do engineers treat a failed test as useful instead of bad?

Sources

NASA JPL Education. (n.d.). Engineering design process flow chart. NASA Jet Propulsion Laboratory. https://www.jpl.nasa.gov/edu/resources/image/engineering-design-process-flow-chart/ IEEE TryEngineering. (n.d.). Engineering STEM lesson plans & activities. https://tryengineering.org/explore-resources/lesson-plans/