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Engineering activity

Build Something to Sell

Build something for a pretend store using recycled materials, then explain why a customer might want it and what makes it special.

Real World MissionAbout 60 minutesScreen-freeParent help expected

Materials and setup

How this changes by age

Pre-K (ages 3–4)

Build something for a pretend store using recycled materials, then explain why a customer might want it and what makes it special.

Difficulty 1 of 3

Steps

  1. Look around the recycled materials (boxes, fabric scraps, rope, tape) and pick a few you like.
  2. Build something simple, like a stuffed-animal house from a shoebox.
  3. Decorate your creation so a 'customer' would want it.
  4. Set up a pretend store display with a sign showing the item's name and price.
  5. Show your item to a parent or sibling and explain why it would be useful or fun and why it is worth that price.
  6. Tell a grown-up one thing that surprised you.

Learning objectives

  • Imagine that something you build has value to other people
  • Practice explaining why a built item has value to another person
  • Use recycled materials creatively to build a finished product

Kindergarten (ages 5–6)

Build a simple toy for a sibling or friend from recycled materials. Decorate it and give a kid-sized sales pitch for why it would be fun to use.

Difficulty 2 of 3

Steps

  1. Pick a simple toy idea: a rubber-band-powered cardboard car, a cup-and-string phone, or a paper puppet.
  2. Gather the recycled materials you need and build the toy.
  3. Decorate it so it looks fun.
  4. Show the toy to a sibling or friend. Ask: 'Would you play with this?'
  5. Present the toy and explain what makes it fun, useful, or sturdy. Add a pretend price tag and say who the toy is for.
  6. Tell a grown-up one thing that surprised you.

Learning objectives

  • Build a working toy from a simple plan
  • Understand that toys are made by people who design and build them
  • Practice presenting a finished product to another person

Early elementary (ages 6–8)

Design and build a dog toy from recycled materials. Test it with a tug-of-war and think like both an engineer and a young entrepreneur.

Difficulty 2 of 3

Steps

  1. Brainstorm: what makes a good dog toy? It should be tough, easy to grip, and fun.
  2. Design your dog toy on paper using only recycled materials (rope, fabric scraps, old t-shirt strips, knotted rags).
  3. Build the toy.
  4. Test it: do 10 hard tug-of-war pulls. Did it survive? If not, where did it break?
  5. Iterate: rebuild any weak spots and test again.
  6. Think like a designer and seller: what would make this toy better for a real dog and owner, and what would make someone choose it at a pet store or market table?
  7. In one sentence, tell a parent or sibling what surprised you today.

Learning objectives

  • Design a product that meets real-world durability requirements
  • Test a product to failure and improve weak points
  • Evaluate how well a design meets a real user's needs
  • Practice basic customer-thinking about what makes a product appealing

Upper elementary (ages 8–10)

Design a useful product under a tight materials constraint. Build 3 prototypes, test them, pick the best design, and frame it like a young maker business.

Difficulty 3 of 3

Steps

  1. Choose a product idea: a planter from a soda bottle, a bird feeder, a phone stand, or your own idea.
  2. CONSTRAINT: use only a small set of low-cost or recycled materials. List your materials and keep the design simple so it could realistically be made more than once.
  3. Build 3 different prototypes. They can use different shapes, materials, or assembly methods.
  4. Test each prototype for the function it needs to do (does the planter hold soil? does the phone stand hold a phone?).
  5. Pick the best prototype and explain why it won.
  6. Give your product a name and a one-sentence pitch for who it is for.
  7. Reflect: what would you do differently next time? What would you change to make the product stronger, easier to use, easier to build again, or easier to sell at a kid business fair?

Learning objectives

  • Design a product within a strict material constraint
  • Build and compare multiple prototypes before picking a winner
  • Reflect on how engineers improve products through prototype testing
  • Practice simple entrepreneur thinking about audience, repeatability, and product pitch

Safety and evidence note

Read the full activity before beginning. An adult should supervise tools, heat, food, outdoor work, movement, and experiments as appropriate. Completion records that the activity was done; the child’s explanation, work sample, photo, or demonstration is stronger evidence of learning than a completion check alone.

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