What's the best way to hang frames without nails?

I have some picture frames that I want to hang in my classroom. I don't want to have nail holes in the walls. What's the best way to do this?? I've used ducktape %26amp; masking tape, but the frames always fall. Could you all give me some suggestions? Thanks so much!What's the best way to hang frames without nails?
Commando hooks by 3M....you can get them at KMart, Home Depot, Michaels...at Michaels they are in the frame section.What's the best way to hang frames without nails?
Blue Tac or 3M commander like hooks. You can find them at craft stores (framing section) and office supply stores, even some discounters. They are great because 3M rates them by the weight of what you are hanging and they do no damage to the wall after you remove them.
There are peel and stick hangers which can be applied to your walls and then just hang the pictures on them the same as conventional hangers. They are easy to remove without damaging your walls. Try Walmart, Home Depot or Walgreens.
..........screws
I have to go with ';eskie';3M stick on hangers, no damage, easy to use. easy to take off. I have used them many times as an alternative to anchors. The only draw back limited to weight, heavier objects require conventional methods.