You are the lead engineer at a yo-yo company. Follow the engineering design process — define, research, design, justify — to create a contest-ready yo-yo.
Real engineers compare options before choosing. Fill in one pro and one con for each material, thinking about cost, durability, and spin time.
| Material | Pro (why choose it?) | Con (what's the catch?) |
|---|---|---|
| Plastic | ||
| Aluminum | ||
| Wood |
1. Circle your choice: PLASTIC / ALUMINUM / WOOD — and write one sentence defending it against the other two.
Label on your sketch: diameter, where the weight sits (center vs. rims), and your yo-yo's name.
2. Why did you choose this shape? (Hint: where the weight sits changes how long it spins.)
3. Which constraint was hardest to meet, and what did you give up to meet it? (Every real design involves trade-offs.)
4. If you could test one thing about your design with a real prototype, what would you measure and why?
Material table — expected answers: Plastic: pro = cheap to mass-produce / tough against drops; con = less rim weight, so shorter spin than metal. Aluminum: pro = weight can be pushed to the rims for long spin (high moment of inertia); con = expensive to machine, dents on concrete. Wood: pro = classic, cheap material, warm feel; con = string wears the wooden axle over time, harder to make precisely.
Discussion points: #2 — strong answers connect rim weight to spin time (mass farther from the axle = harder to slow down). #3 — look for an honest trade-off, e.g. "I wanted aluminum for spin but plastic survives drops better." #4 — good answers name something measurable: sleep time in seconds, weight in grams, diameter in mm. There are no wrong designs — grade the reasoning, not the sketch.