Swimmers know to float by turning their bodies horizontally rather than vertically, but why does that make a difference? In an interesting lesson plan, scholars explore buoyancy and the properties of air and water. They test cups to see which float to determine the variables that relate to buoyancy. Then, they build Cartesian divers and relate buoyancy to scuba diving and submarines. 

Concepts

buoyancy, mass, density, displacement, volume, force, buoyant force, water density, water displacement

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Additional Tags

science

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Instructional Ideas

• Discuss what would change if class members repeated both experiments using oil instead of water
• Extend the lesson by having pupils build boats out of aluminum foil to see which can hold the most weight

Classroom Considerations

• Each pupil needs an empty two-liter bottle

Pros

• Includes background for both the teacher and pupils
• Uses common, cheap materials
• Easily adapts to higher or lower levels of prior knowledge

Cons

• None

Common Core

SL.6.2 RST.6-8.3 RST.6-8.4