The Earth isn't round.
Yup, up is down, black is white, the Earth is no longer round ...
OK, let's be real. The Earth didn't one day suddenly slim down, develop a bulge or turn into a triangle. It's never been round, and it was Sir Isaac Newton (who just had to put his nose in everything) who said it was actually an oblate spheroid. So just tell the kids that.
Perhaps you're not familiar with the term? Imagine a lovely, round ball of clay. It's sitting on the table peacefully. Unable to stand its perfect plumpness, you place your hand on the top of the ball and press gently. The ball begins bulging in the middle, while the rounded top and bottom flatten out a bit. The result? An oblate spheroid.
That's what we mean when we say the Earth is round. It's actually a bit bulky in the middle, much like the stomach of a middle-aged man. And the shape isn't entirely constant; earthquakes and plate tectonics change the figure of the Earth. You might not know that Earth tides -- the gravitational pull of the sun and moon on land -- affect our planet just like ocean tides. As the Earth spins, it will redistribute mass back to the equator in a process termed true polar wander [source: Choi].
Now that you're prepared to be Super Science Parent and blow your kids' minds with Earth facts, check the next page for more great links that will astound.