Grouping: Pairs
Take-home: Filter column model
Key ideas: Filtration vs purification, particle size, layered media, fair comparison.
Start with: Pour identical dirty water through gravel alone and a layered filter.
Success check: Compare clarity, flow time, and volume recovered; never call filtered water safe to drink.
Try changing: Layer order; depth; particle size; flow rate.
Preparation: Wash media; pre-cut bottles; create explicit 'do not drink' labels.
CNC preparation: Cut filter stands if using cardboard.
3D-print preparation: Print reusable bottle/filter stands.
Lesson flow: Day 1: design/build
Day 2: test + improve
Video:
Make a Water Filter
Safety and cleanup: Filtered water is NOT for drinking; goggles; wash hands; control activated carbon dust.
https://www.sciencebuddies.org/science-fair-projects/project-ideas/EnvEng_p030/environmental-engineering/how-filtering-can-clean-water
https://www.youtube.com/watch?v=bqcll80EwWk