You might like to discover this book from the 5-6 booklist.
Heroes of Olympus, The: The lost hero
"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 someone called Leo, and they're all students in the Wilderness School, a boarding school for "bad kids."
Piper has a secret. Her father has been missing for three days, and her nightmares reveal that he's in terrible danger. Now her boyfriend doesn't recognize her, and when a freak storm and strange creatures attack during a school field trip, she, Jason, and Leo are whisked away to someplace called Camp Half-Blood.
Leo has a way with tools. His new cabin at Camp Half-Blood is filled with them. What's troubling is the curse everyone keeps talking about, and that a camper's gone missing. Weirdest of all, his bunkmates insist they are all-including Leo-related to a god."
Riordan, Rick