Wonders of modern machines
The teacher was discussing the wonders of modern science, and in particular, various kinds of machines. Asking the nine-year-olds to name the most wonderful machines they had ever seen, she got all the stock answers --- airoplanes, televisions, robots, etc. until once thoughtful little girl answered, "A hen!"
"Why, Maudie," said the teacher, "what-ever makes you think a hen is a wonderful machine?"
"Well," said Maudie, "do you know anything else that will take all our left-overs and turn them info fresh eggs?"