Two subjects I've always been fascinated by are twin studies, and space exploration -- an unlikely pairing which, in the mission of Scott Kelley, has enabled scientists to glean data, as never before, on the effects of spaceflight on the body.
You can watch all the episodes of Time'sdocumentary, "A Year In Space," here; and find learning activities based on the series here and here. Visit the following sites for additional free resources about astronauts and space:
All About Spacesuits: This interactive resource, created by NASA, explains how a spacesuit functions as a personal, mini-spacecraft that enables an astronaut to live and work in the harsh space environment. Learn about the suits worn for the Mercury, Gemini, Apollo, shuttle, and spacewalk missions.
Space Exploration Mini-Unit: Seven lessons, with articles and videos, beginning with how to become an astronaut, and culminating in the future of space exploration.
Train Like an Astronaut: Combine learning about the requirements of space exploration with physical fitness. This site offers videos and free activity guides that explain how exercise and proper nutrition help astronauts maintain and improve important aspects of fitness such as physical strength, endurance, speed, flexibility, balance and coordination.
Astronaut Videos: See how astronauts eat, sleep, brush their teeth and do other tasks aboard the International Space Station.