A very old one that still works:
Wise guy: Spell “joke.”
Kid: J-O-K-E.
Wise guy: What do you call the white of an egg?
Kid: The yolk.
Wise guy: No! You call it the white (or the albumen, if you’re a show off).
If four people can dig four holes in four days, how long will it take two people to dig half a hole?
There’s no such thing as half a hole.
The square root of a number is any number that can be squared to provide that number. Hence, the square root of 9 is 3 or -3, because -3 * -3 = 9.
How long was the One Hundred Year War?
Oh, wait… 
116 years. From 1337 to 1453
OK – How long was the Six Day War, then? Yup, you guessed right this time… 6 days 
That also works for the Thirty Years’ War:
which was exactly 30 years long: 1618-1648
Huh…and here I was thinking it’s a nun in a blender.
How Long is a Chinese man.
This one can only be spoken, of course.
Aren’t white horses classified as “grey” (unless they are albinos)?
Brian
BZZZZT! I think this covers either situation.
Well, the answer’s the same, but not for the reason you’re thinking. Moses did have an ark. Exodus 2:3.
How much dirt is in a hole six feet deep and four feet wide?
A ship is at anchor at low tide. There is a rope ladder hanging over the side, just touching the water, and the rungs are one foot apart. How many rungs are under water after three hours if the tide rises one foot per hour?
I’ll bite…one?
Psst… Moses was the Red Sea parting dude, not the ark guy.
Well, actually Moses had an ark, just not the kind full of animals.
John’s mother has three children. The oldest child is named April. The middle child is named May. What’s the youngest child’s name?
John.
I dispute that answer.
You can walk all the way into the woods, at which point, you are in the deepest part of them. Walk any farther, and you are now more than halfway through the woods.
How do you put an elephant into a refrigerator?
What kind of noise annoys an oyster?
A noisy noise annoys an oyster.
How do you tittilate an ocelot?
Oscillate its tit a lot.
Ok, not suitable for 10 year olds but still the perfect counterpoint.
I suppose a ten-year-old is too young for the similar “How do you titillate an ocelot?” joke though.
what’s the largest human hand?
11 inches. If it was any longer it would be a foot.
