Here is a challenging question for all of you who like a...well, challenging question

NOTE: If you have heard this before, know the answer, or think you have figured it out, reply to the thread, but make your reply HIDDEN by simply checking the 'Hide this Post' checkbox so that others will not see the answer if they want to try figure it out.

You are in the attic of a building. On the wall there are three numbered light switches.
Down in the basement are three numbered light bulbs, each is connected to one switch. You don't know which switch is connected to which light. All the bulbs are swithced off to start with.

You can do what you like with the switches, but once you leave the attic, the attic door will lock and you can't get back in.
The only place you can go to is the basement (three floors down), where the light bulbs are.

You have to figure out which switch is connected to which light bulb.

If you need any clarifications or anything, just reply with your questions.