Cartesian Diver

We make a Cartesian diver using a drinking straw and sticky tack. When the diver is placed in a sealed bottle of water it can be controlled by squeezing and releasing the bottle, which makes it rise and fall within the water.

Physics - Forces - Learning Points.
Buoyancy can be controlled by changing the volume of a submerged object.
Some fish and submarines use a similar principle to the Cartesian diver to control their buoyancy.

A Twig Experiment Film.
Let students experience real experiments in lab conditions anywhere, from setup, method all the way through to analysis and real-world application.