I love clean kid jokes and riddles. Here’s a bunch for back-to-school:

Q. Where do New York City kids learn their multiplication tables?
A. Times Square!

Q. Why doesn’t the sun go to college?
A. Because it has a million degrees!

Q. What did the math book say to the other math book?
A. “I’ve got problems.”

Q. What did the calculator say to the other calculator?
A. “You can count on me!”

And you can never go wrong with a chicken joke:

Q. Why did the chicken cross the road?
A. To get to the other side.

Q. Why did the chicken go up the stairs?
A. She was already across the street.

Q. Why did the hen cross the road?
A. To prove she wasn’t a chicken!

Q. Why do hens lay eggs?
A. Because if they dropped them they’d break!

Q. Which side of a chicken has more feathers?
A. The outside.

Finally, you can always throw ’em off balance by ending the chicken jokes with a good horse joke:

Q. A cowboy rode into town on Thursday and stayed 2 nights and left on Tuesday. How is that possible?
A. His horse was named Tuesday.

There’s many more here at the source.