The Naughty Pupil

I could vividly remember one day while I was still in my primary school. Our Chemistry teacher entered the class. We were to discuss about elements. This dialogue ensued:                     Teacher: good morning pupils.             Pupils: good morning aunty.                        Teacher: today we shall discuss about elements, but before we proceed, can anybody give us an example of an element? (I raised up my hand,being one of the most brilliant pupils in class!)             Teacher: okay, Basic, help us out.                I: Oxygen                 Teacher: good,any other example?(Ade raised up his hand)        Ade,give me an example of another element.                     Ade: another Oxygen ma!