TOPIC:

Astronauts in microgravity experience many unusual effects on their bodies from their environment. One of these is that after some time in microgravity, they find that they are slightly taller. This is caused by the expansion of sections of the spinal column, as it is no longer compressed by gravity.
Since we cannot easily create a long duration microgravity environment in the classroom, this demonstration instead models this effect with the expansion being caused by a change in air pressure. A column of discs is separated by marshmallows, and the whole placed into a vacuum chamber. As the pressure is reduced, the gas in the marshmallows expands, forcing apart the spinal discs. When pressure returns, the spine collapses back, much like astronauts experience when they return to Earth.

Challenge your students to think of other body parts and processes that could be similarly affected by changes in gravity.