What's black and white all over and difficult?
An exam paper!

Why aren't you doing very well in history?
Because the teacher keeps asking about things that happened before I was born!

Who invented fractions?
Henry the 1/8th!

The Spanish explorers went round the world in a galleon.
How many galleons did they get to the mile?

What kind of lighting did Noah use for the ark?
Floodlights!