Videos of experiments you can't do at home, interactive games (mostly drill with simple graphics and no audio), a glossary, and science answers section.
My son could probably get lost in this site~ a chronological timeline of the story of DNA, interactives in learning about DNA along with lesson plans etc..
a site I came across appropriate for upper grade levels, an abundance of information here from the compound library, to quiz's,interactives, articles, glossary, a great resource for chemistry