How do you retrieve something you lost?

Okay, so here’s what happened.
1. Yay! School’s out.
2. Packing up….
3. At home, doing my homework. OH NO! Where the heck is my graphing calculator?
4. At school.
5. Worry worry worry
6. “Oh, (Bob) has it!” My friend says.
7. “Bob, I want my calculator now!” I say.
8. Bob: “Oh, you left it on the ground. I gave it to an 8th grader because she said she knows you.”
9. Me: “What 8th grader? I don’t know any!”
10. Bob: Uh oh….
So now, what do I do?