A: It takes me hours to find my classroom. B: I might be able to help you. A: Really? That would be great! B: What's your classroom number? A: My classroom number is A21. B: So the "A" is the building type. A: Okay, but I don't know where that is. B: Do you know where the gym is? A: Yeah, I do. B: Okay, your classroom is behind the gym. A: That's really helpful! Thank you. B: No problem, and the "21" means it's upstairs.
