The teacher had asked each child to bring one electrical appliance into school for "show and tell". "What did you bring, Mary?" asked the teacher. "I brought a kettle." "And what is it for?" "It's for boiling water." "That's very good, Mary," said the teacher. "Now, Billy, what have you brought for us?" "I brought an electric can opener," said Billy. "It opens cans, miss." "Well done, Billy," said the teacher, "but I see that Johnny hasn't brought anything." "Yes I have, Miss," said Johnny. "It's in the corridor." The whole class looked out into the corridor. "What's that, Johnny?" asked the teacher. "It's a heart/lung machine," replied Johnny. "They use it in hospitals to keep your heart going." "I see. And what did your father say about it?" "Aaaaaaaahhhhhhh!" SCIENCE AND TECHNOLOGY