Would a baggie filled with water have the same shape sitting on a table as it would in a bucket of water? Why not? Allow learners to find out first-hand the effects of gravity acting alone on the baggie, as well as when gravity is counteracted by buoyancy. In the first lesson of a unit on muscles and bones, kids begin to understand how water is similar to a microgravity setting, such as on the International Space Station. While the lesson may not seem to have much to do with muscles or bones, it is referred to in other lessons in the unit when talking about astronauts training for space in Earth's closest thing to a microgravity environment: under water.