1st day:- techer: good morning pupils, puplis: good morning sir, teacher: what subject do we have today? Pupils: Maths,sir, teacher: how can it be? Let me go and check my timetable (so our teacher went out and never came back). 2nd day:- teacher: do u know what u have today? Pupils: Yes!! Teacher: Then it's no use teaching u what u already know. 3rd day:- teacher: do u know what u have today?, Pupils: Yes!, no!, teacher: good let those who know teach those who dont know..