Kindle Unlimited, or KU, is a service run by Amazon where you can sign up for a monthly fee and then read as many books that are available in the KU library as you want. (You can only borrow 10 books at a time, but you can return those 10 books and get new ones whenever you want.) If you read a lot and you read quickly, this is great option to read books for a very low price. (When you are browsing books on Amazon, you can tell if a book is in KU or not by looking for the small words Kindle Unlimited just above the book cover.)
(*I just want to point out that I’m not affiliated with the Kindle Unlimited program in any way. I just enjoy the service.)
There are books for all ages and of all genres in Kindle Unlimited. Here are some awesome middle grade books in KU:
Jason has a problem. He doesn’t remember anything before waking up on a school bus holding hands with a girl. Apparently she’s his girlfriend Piper, his best friend is a kid named Leo, and they’re all students in the Wilderness School, a boarding school for “bad kids.” What he did to end up here, Jason has no idea—except that everything seems very wrong.