Apparently I missed the memo.  Maybe I'm just not pretty enough to be on the mailing list.

The store Forever 21 sells a magnet that reads, "I'm too pretty to do math."  You can read about it (with excellent commentary) on the blog Sociological Images.

This reminds me of the sad fact that even though more girls than boys initially signed up for my higher level high school calculus course, all but three of those girls dropped it when they found out how difficult the class would be.  I almost dropped it myself, but the teacher convinced me to stay.  I am so glad she did.  

In my years studying math and tutoring math, I've found that girls more often than boys have low self-esteem about their ability to do math, and they tend to just quit when the going gets tough.  There is nothing different about girls' and boys' ability to do math, and you can be sure that looks have nothing to do with it.
Pendulums are fascinating mathematical and physical objects.  We use them all the time, though we don't usually realize it.  Early clocks relied on the regularity of pendulums to keep time accurately.  Swings are pendulums.  Did you ever notice that the long rope swings swing farther and slower than the regular swings at the playground?  When I was a kid, we used to throw the swing over the bar to shorten the chains (at the disapproval of our teachers).  We figured out that this made the swing go really fast.

So I've got you thinking about pendulums and what you know about them... I now share with you one of the most beautiful mathematical videos I've ever seen: