A mousetrap is used to demonstrate the all-or-none principle of muscle contraction. Just like a muscle fiber, the trap either snaps fully or not at all when triggered by a stimulus.

1. Set a mousetrap carefully according to its standard setup.
2. Hold up a pen or pencil to represent the stimulus.
3. Apply force with the pen or pencil to trip the mousetrap.
4. Show that the trap snaps completely once triggered, not partially.
5. Compare this action to the way a muscle contracts in an all-or-none fashion when stimulated.

📄 Mouse Muscle Contraction (Page 20 of pdf) - Author: https://www.link.link2

• Pair with a nerve impulse demonstration to show how signals trigger the contraction.

• Handle the mousetrap carefully to avoid pinching fingers.
• Keep fingers and hands away from the snapping mechanism during setup.
• Use a pen or pencil, not fingers, to trigger the trap for safety.

• Why does the mousetrap snap completely rather than partially?
• How does this model demonstrate the all-or-none principle of muscle contraction?
• In what way do real muscles differ from this mousetrap model?