Though Windows to the Universe is basically a science site, it has many links that will connect science with language arts, history and math. Find an abundance of information and activities for your classroom. There are numerous science categories, and within each category you can choose "Beginner," "Intermediate," or "Advanced." This site has excellent visuals and numerous topics, and several educational interactives (under "Games"). Don't miss it!
This is one way to solve the email problem with students. You can set up a teacher gmail account and then add student sub accounts. Watch the Jing screencast.