Geology Professor: Does anyone know how old the Earth is?
Student at the back: Oh, oh! I do! Four billion and three years!
GP: Hmm, how did you get that number?
SatB: Well, I flunked this class three years ago but I remember you said four billion years then.
Geology Professor: These students today are all alike. They look the same, they dress the same, and they have the same hair. How do tell the difference between the boys and the girls?
Biology Professor: Oh, that's easy. You look into their genes.
The afternoon was hot, and the professor noticed that Billy was drowsy. Resolving to wake him up she asked, "Tommy, if the distance to the sun is 93 million miles and the first president of the United States was George Washington, how old am I?"
"You're forty-eight", answered Tommy promptly.
"My goodness, how did you know", said the surprised professor.
"That's easy", said Tommy. "My brother's twenty-four and he's only half crazy."