Black balls

A 5th grade teacher tells her class that she is going to ask a question on thursday and whoever gets it correct will get friday off. S thursday comes and the teacher says "Ok class its time for our question. How many gallons of water are in the Atlantic Ocean?" the kids look at each other teacher says " nobody knows nobody gets friday off. So the next Thursday comes around and the teacher says "Ok class its time for our question to get friday off. How many grains of sand are in the Sahara desert?" kids look very confused, teacher says " nobody knows nobody gets friday off" Well little Johhny sees whats going on teacher is just gonna ask impossible questions so he gets an idea, he goes home gets into his dads golf bag takes out 2 balls and paints them black. Thursday comes along and the teacher anounces "Ok class its time for our question" little johnny reaches in his book bag takes out the golf balls and rolls to the front of the class hitti