Sound is just vibration your ear can hear. A short unit, a hands-on build, and a real-world fix — no equations that outrun the concept.
The Path Through Unit 3
Build a working instrument out of scraps — rubber bands, straws, paper, wood, whatever you've got — tune it using what you know about frequency and wavelength, then record a music video with it.
Sound from the band room is leaking into the library next door. Using what you know about how sound reflects, absorbs, and resonates, diagnose the problem and propose a fix that fits a real materials budget.