PBS Jazz Possibly the best site for elementary students. An entire area is devoted to lessons for children.
Jazz at Lincoln Center Great resource for teachers. Many educational programs and watch for a new jazz curriculum to come out soon.
Jazz in America Jazz Curriculum project for music and social studies teachers. 11th grade is online now. 8th grade will soon be online and next year 5th grade. Jazz Roots Great web site for researching and learning about early jazz history. Lots of period photos.