An array of mousetraps loaded with ping pong balls is used to simulate a chain reaction, showing how one event can trigger many others in quick succession. The setup visually models nuclear chain reactions in a safe and dramatic way.

1. Assemble a 6 × 7 array of mousetraps on a plywood board.
2. Load each mousetrap with two ping pong balls.
3. Demonstrate with a single mousetrap by setting it off with a stick and showing how one ball is released.
4. With the plexiglas cover off, drop a ping pong ball onto the array to show limited reactions without containment.
5. Place the plexiglas cover over the array to contain flying balls.
6. Drop a rubber ball through the side hole of the box to set off a large chain reaction across the mousetrap array.

Mousetrap Fission - Harvard Natural Sciences Lecture Demonstrations:

Mousetrap Chain Reaction - SFU Physics:

📄 Mousetrap Chain Reaction - Simon Fraser University: https://www.sfu.ca/physics/demos/demos-experiments/mousetrap-chain-reaction-burnaby.html#:~:text=Arm%20the%20single%20mousetrap%20with,a%20nucleus%20and%20the%20mousetrap.

📄 Nuclear Fission with Ping Pong Balls (variation with students throwing) - ANSTO: https://www.ansto.gov.au/media/2830/download

• Use fewer mousetraps to make a smaller-scale version.
• Replace ping pong balls with cork stoppers for different reaction dynamics.
• Explore electronic mousetrap simulations to avoid manual setup.
• Have each student hold two ping pong balls; when struck by a flying ping pong ball, they throw both of theirs into the air to extend the chain reaction into the classroom.

• Safety glasses required.
• Handle mousetraps with extreme care to avoid accidental triggering.
• Always keep hands and face away from armed mousetraps.
• Use a plexiglas cover to contain flying ping pong balls during the full chain reaction.
• Ensure demonstration is conducted only in a controlled classroom or lecture setting.
• If students participate in the variation, ensure they stand well back from the mousetrap array to avoid injury.

• How does this demonstration model a nuclear chain reaction? (Each mousetrap represents a nucleus, and releasing balls shows how one reaction can set off many others.)
• Why is the plexiglas cover important? (It prevents injuries from flying ping pong balls and allows safe observation of the reaction.)
• What factors determine whether the chain reaction spreads quickly or fizzles out? (The density of traps and whether enough energy is released to trigger nearby traps.)
• In the student variation, how does throwing balls in the air represent neutron multiplication? (It simulates how one reaction in a nucleus can release multiple neutrons, which can then cause additional reactions.)