Make buoyancy click with a seasonal engineering lab: students design a small foil “bog boat” that carries the maximum mass (cranberries/coins/washers) before sinking. They plan, build, test in a water bin, record data, and iterate to optimize stability and displacement—perfect for stations or a full-period lab. What students do Plan & sketch under material/size constraints, predict capacity. Test in rounds, adding equal-mass items until failure; record max mass, freeboard, and failure mode.