During class, the chemistry professor was demonstrating the properties of various acids.

“Now I’m dropping this silver coin into this glass of acid. Will it dissolve?”

“No, sir,” a student called out.

“No?” queried the professor. “Perhaps you can explain why the silver coin won’t dissolve.”

“Because if it would, you wouldn’t have dropped it in.”

Little Johnny wanted to go to the zoo and pestered his parents for days.

Finally his mother talked his reluctant father into taking him.

“So how was it?” his mother asked when they returned home.

“Great,” Little Johnny replied.

“Did you and your father have a good time?” asked his mother.

“Yeah, Daddy especially liked it,” exclaimed Little Johnny excitedly, “especially when one of the animals came home at 30 to 1!”