Assess students' ability to apply density and buoyancy principles to design, calculate, and test a model boat that must float and carry a specified load. Tasks require using Archimedes' principle and density calculations to determine hull volume and material choice, estimating buoyant force and safety margin, predicting floatation with a given mass, addressing stability (center of mass) and displacement, creating a simple design sketch, performing basic calculations (volume, mass, weight), and planning or interpreting a prototype test. Suitable for formative or summative assessment at grade 6–8 with medium complexity and an "apply" cognitive goal.