Grouping: Individual or pairs
Take-home: Working rollback can
Key ideas: Stored elastic energy, rotational motion, internal mechanisms, energy transfer.
Start with: Roll a completed can away and let it mysteriously return.
Success check: Can rolls away, slows, reverses, and returns at least partway.
Try changing: Rubber-band tension; internal mass; can diameter; starting push.
Preparation: Pre-punch/prepare any holes and build one reliable example.
Lesson flow: Day 1: Reveal mechanism → assemble → roll trials → adjust internal mass/tension
Video:
Magic Rollback Can - Sick Science! #051
Safety and cleanup: Teacher prepares holes/cutting; internal weights must be secured; use floor lanes.
https://www.youtube.com/watch?v=bQyK47SBkHw
https://drive.google.com/file/d/1Hz48AOL5kHINzy6MNTo9fQoyjz3t6EhC/view?usp=sharing