NASA
Nasa: Mysteries of the Sun
Learn about the study of the Sun's influence on the solar system called Heliophysics. This site contains videos on topics like Space Weather, Solar Variability, the Heliosphere, Earth's Magnetosphere, and the Earth's Upper Atmosphere.
NASA
Nasa: Heliophysics: New Science of the Sun Solar System Connection
This site from NASA lists common and uncommon misconceptions about Sun-Earth Science. Site also provides links to activities and lesson plans as well as background reading.