Hank's suggestion is great. It was my first heli. Very easy to fly.
Here's one I just found recently that might just fit the bill as well.
I think it might be a little better suited as it already has a winch and magnet to carry stuff, and it has circuitry built in to protect the motors and speed controllers in case of a crash or bad landing, which would be a big plus with a group of high-schoolers. Only drawback I could see would be the 3 wheels may not be as stable on the ground as the CX2 skids. I'd search around for customer reviews.