The Federal Government's Office of Citizen Services and Innovative Technologies, part of the U.S. General Services Administration. Has created Kids.gov to help children and families be better informed. Two of their webpages have some great resources for getting ready for school.
This first web page has "Ten Tips to Get Ready for Back to School" so parents know what to do to have their children ready to learn.
The second webpage has helpful study information for different school subjects, online safety, health, exercise, and how parents can be more involved in the child's education.