35 min
Frozen Treasure Excavation
Freeze small toys in a tub of water and let them dig them out.
🎯
Cardboard Marble Run
Kitchen roll tubes taped to a wall, and a marble that keeps falling out.
A real engineering problem with instant feedback: either the marble makes it to the bottom or it does not.
What you need
- cardboard tubes
- masking tape
- a marble or small ball
- scissors
- a wall or large box
How to do it
- Cut some cardboard tubes in half lengthways to make open channels.
- Tape the first one to a wall or the side of a large box, sloping downwards.
- Drop the marble in and see where it comes out.
- Add the next section wherever the marble actually lands, not where you planned.
- Keep going until the marble reaches the floor without escaping.
Why this is good for them
This is iterative problem solving with immediate, unambiguous feedback, which is rare and valuable. Children learn that a design that fails is information rather than a mistake, and that adjusting one section is more effective than starting again.
Adapting by age
4 to 5 yearsTwo sections only, and tape them yourself while they direct.
10 to 12 yearsAdd a rule: it must include one loop, or the marble must take at least five seconds.
Keep it safe
Marbles are a choking hazard. Do not use this with under-threes in the house. Adult does the cutting.
Cleanup tip
Masking tape peels off paint cleanly. Test one strip first if the wall is freshly painted.
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