Book suggestions for elementary aged kids

I teach at a daycare center and I am the lead teacher in the School Aged Room. I am trying to find suggestions for books that we can read in the classroom this coming summer. I would prefer a series that the kids can follow along with throughout the summer. Any suggestions for Books for elementary aged kids?

I will have 1st-5th grade kids, so I need something that will appeal to 6-11 year olds.