Here are some amazing resources for summer reading selections:
Check out the summer reading programs at your local public library. This summer, visit Boulder Public Library to register for the summer program: Summer of Discovery 2018. Students can track their reading, earn rewards, and attend special events. Other local libraries and bookstores have their own fun programs to check out as well. https://boulderlibrary.org/summer/
A terrific all-around book site. Definitely explore this one.
If you are curious about the level of a specific book, you can google the title with “guided reading level”. (Generally the levels correspond to grades in the following way: Kindergarten Levels A-D, First Grade Levels D-J, Second Grade levels J-M, Third Grade Levels N-P)