The Moon has no air, so sound can't travel there.

Red blood cells travel all the way around your body in about one minute.

The Mariana Trench is the deepest part of the ocean — almost 7 miles deep.

The ancient Egyptians built the Great Pyramid of Giza more than 4,500 years ago.

The first jack-o'-lanterns in Ireland were carved from turnips and potatoes, not pumpkins.

Sea otters hold hands while they sleep so they don't drift apart.

Kangaroos can't walk backwards.