How about an oldie….
You are standing outside of a room without windows and a single door. The only thing in the room is a single incandescent light in the center or the room. There is weatherstripping around the door so no light "leaks" out the cracks around the door.
Outside the door (where you are) there are three identical light switches. You can flick any or all of the switches as many times as you like, however, once you open the door - you cannot tough the switches any more and you must immediately identify which light switch actually operates the light.
How are you going to determine the correct switch?
Never mind. I think i got it.
Light switches usually say on of off on them (unless they are three or four way switches)
The clue is incandescent bulb. They get hot when turned on.
Solution A
If all switches are off to start, turn on any two for ten minutes then turn off any one of the two that you turned on.
Open the door.
If the light bulb is on then the switch that is on is the one that works the bulb.
If the light is off, then walk over to the light bulb and touch it. If the bulb is hot, then the correct switch is the one that you just turned off.
If however the bulb is cold then the correct switch is the one that you never turned on.
Solution B
If any of the switches are on then turn off all switches for about thirty minutes to let the bulb cool then apply solution A
If you turn on the lightbulb and leave it for a few minutes, it would heat up.
So, if you try the first switch for a minute, then turn it off. If you then turn the second switch on, and go inside you will be able to know as:
- If the bulb is hot and off, then its switch one.
- If its cool and off then it cant be switch one or two, and has to be switch three?
Jimbo1
would never have figured this one out. 
.
Waiting for next Monday