How does the absence of gravity affect the human body? The skeletal system, circulatory system, and the sense of balance are all impacted. With a very casual tone, an astronaut explains the changes to these body systems and also an experiment done by neuroscientists on underuse of organs. The video is presented as if you are in a spacecraft viewing each topic within a window. Although it doesn't directly meet science standards, it would be an interesting addition to a unit on space exploration. Follow it with a discussion about why astronauts need to be in top physical condition before embarking on a mission.