NASA
Nasa Cosmology: The Study of the Universe
Cosmology is the study of the "large scale properties of the universe as a whole." In this set of sites, NASA provides information on the Big Bang Theory in a simplified language. The beginning, evolution, structure, fluctuations and...
Other
Montana State Univ.: Expanding Universe (Lesson Plan)
This site has a lesson plan in which students gather evidence supporting the Big Bang Theory using a balloon model of the expanding universe.