my computer sci. teacher asked this to my class today for a bonus point and now i'm really curious what the answer is:

You are standing outside a windowless room, in which there are 3 light bulbs. In front of you are three switches. You cannot see into the room, but you are allowed to enter the room once to examine the bulbs. How can you determine which switch controls which bulb?

any ideas? i can only figure out one how to determine one bulb...