American Geosciences Institute produces K-5 GeoSource which is a site that hosts lesson plans and other educational resources for teachers. K-5 GeoSource has a very Web 1.0 look to it, but if you do a little digging you'll find some helpful materials. A few of the resources that I looked at were this free chart about types of rocks (link opens PDF), a science fair project guide, and a short Earth scientist career guide.
Applications for Education
As I mentioned above, K-5 GeoSource isn't the fanciest site you'll find on the web and it lacks any kind of interactive element for students. If you just need to find some ideas to use in your classroom, K-5 GeoSource could be worth bookmarking. The most useful aspect of the site might be the science fair project guide that you and your students could work through to plan a hands-on Earth science project.