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Indoor activity

Cardboard Coin Sorter

Build a working coin sorting machine from a cardboard box with slots of different sizes — drop coins in the top and watch them sort themselves!

Ages 5-12 0-1 hours Education 9/10

Materials

  • Cardboard Boxes
  • Coins
  • Markers optional
  • Ruler
  • Scissors
  • Tape

Illustrated Steps

1

Prepare the Box

Stand a shoebox on its side. Cut a cardboard ramp piece to fit diagonally inside.

2

Cut the Sorting Slots

Measure your coins. Cut slots in the ramp — smallest first, each one slightly wider than its coin.

3

Assemble the Machine

Tape the ramp inside at an angle. Add dividers below to create compartments for each coin size.

4

Test and Label

Drop coins in to test. Adjust slots that are too tight or wide. Label and decorate your machine!

What You’ll Create

Ka-ching! 🪙 Your young engineers will build a real working coin sorting machine from a cardboard box! Cut slots of increasing size into a ramp inside the box — small coins fall through the first slot, medium coins through the second, and large coins roll to the end. Drop a handful of mixed coins in the top and watch them sort themselves by size. It’s like magic, but it’s engineering!

Have fun!

  • 💰 Sort all the coins in the house — how much money is there in total?
  • 🏦 Build a slot in the top to make it a combined sorter and piggy bank!
  • 📊 Count how many of each coin type you have — make a bar chart!
  • 🔬 Experiment with coins from different countries — will they sort correctly?

Why It’s Amazing

  • Engineering Design: Building a machine with moving parts that actually works is authentic engineering — designing, building, testing, and iterating. ⚙️

  • Measurement Skills: Measuring coin diameters precisely and cutting slots to match teaches practical measurement and the importance of accuracy. 📏

  • Maths Connection: Sorting, counting, and totalling coins naturally incorporates addition, multiplication, and understanding of monetary value. 🔢

  • Problem-Solving: When a coin gets stuck or goes to the wrong slot, troubleshooting develops critical thinking and patience. 🧠

Pro Tips

For ages 5–7: An adult should do the cutting. Let the child measure the coins with a ruler and help decide slot sizes. Focus on the excitement of testing — the moment a coin rolls and drops perfectly is incredibly satisfying!

For ages 7–10: Let them measure and mark the slots themselves. Guide them through the logic — why does the smallest slot come first? What happens if you put the biggest slot first? Discuss how real coin-counting machines work.

For ages 10–12: Challenge them to build a completely enclosed machine with only an input slot at the top and labelled output trays at the bottom. Can they add a coin counter mechanism? Research how banks sort millions of coins.

Secret Pro Move: Cover the ramp with smooth packing tape — coins will slide much more smoothly than on rough cardboard, making the sorting action faster and more reliable! 🎯