One day, a teacher took his pupils to a chicken farm to pay a visit. When they came near the incubator, chick just got out of its egg shell. "It's wonderful to see a little thing come out from the egg shell, isn't it？" the teacher said. "Yes, sir." said one of the boys, " but it would be more wonderful if we knew how a chick gets into its eggs hell beforehand." 一天，老师带学生到养鸡场参观，当他们走近孵化器时，刚好一只小鸡破壳而出。
“看见一个小生命从蛋壳里出来，岂不是很奇妙的吗？”老师说。
“是的，老师。
”一个男学生说，“可是，如果我们知道它是怎样事先钻进蛋壳里的那就更奇妙了。