For the most part you will probably be given the work that the normal full-timers dont want to do, IE: unbox this, ship that, clean over here, re-organize this, or the occasional project no one else wants to deal with. This is usually to test both your willingness and abilities, and depending on how you perform they will give you more complicated stuff (they will probably try to pawn as much work off on you as they think you can handle without messing up and forcing them to re-do) As far as experience goes, you will probably benefit the most from getting used to the business processes, even though they vary from place to place and depending on your level of involvement it may also help you get an understanding of what areas within IT do what jobs, as most computer science curriculum's will generaly train you as a "jack of all trades" (again this will vary alot from place to place)

I find the best method is to restrict their access, eventually they will learn that if they can't surf the web safely (and actually read all the things they click on), they wont be able to install all those "fun" plugins and programs they want so bad.

I would start them off with some of the Lego\K'Nex sets that involve motors and moving parts. IMO its better to start them off learning a stage at a time, ie, learning to build the frame, understanding how a moving part fit into the frame, etc. Rather than plopping a pile of nuts, bolts and wires in front of them and getting that deer in the headlights look.