Summer reading programs are running at full force this summer, so don't feel it's too late to jump into the fray. Children can lose so much over the summer months, and reading can keep them at grade level or even accelerate them above. Don't forget to review math concepts too --- you don't want your third grader forgetting his or her times tables because of disuse!
Do all you can to keep reading fun and enjoyable. That may mean letting your 8 year old read Pokemon comic books with other books occasionally slipped in. Whatever interests your child is what they will enjoy reading most.
Your local library likely has a summer reading program, but there are others. Here are two I highlighted late this spring:
Barnes and Noble's Summer Reading Program
TD Bank's Summer Reading Program