Students sort 36 statements about buoyancy, density, the buoyant and gravitational forces, and other concepts related to fluid mechanics, into three categories: Always True, Sometimes True, or Never True. They are challenged to justify their decisions using examples, definitions, and exceptions to show why they classified a statement the way they did. This can be a group or individual activity, can be done in class or as homework, and as a formative or summative activity. An editable PowerPoint