There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.
You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)
Your task is to then determine which switch controls the bulb?
The teacher told the student that if he told a lie then he will be expelled from school and if he told the truth then he still is expelled from school.
What can a student say to prevent his being expelled from school?