You're the supervisor, but your forum handle is Orphan? Ok.
To answer this Q, we'll need more, and more specific, information.
1. How many barbells?
2. Are they standard 45lb, 7 foot long bars, with the standard sized circumference on which to load plates?
3. How many stations do you have to squat, press, and bench press out of?
4. How many of each kind of weight plate do you have?
5. How many kids will be lifting at once?
6.. Can you stagger their yard time, or does everyone have to go at once?