# Math Geek Mom: Brain Exercises

Puzzles with a purpose.

## By

September 24, 2015

When I teach Statistics, I usually begin by seeing if there are any two students in the class that share the same birthday. We begin with January, and, if there are no matches, go on to February. In my twenty five years of teaching Statistics, I have had only a handful of classes with no match in them. This, I explain, is because all people who live or have ever lived share only 366 possible birthdays (including February 29th.) Statistics tells us that, if you have more than about 25 people in a room, there is a 50% chance of having a match between birthdays. I tell them that it is my goal to teach them some statistics, and to teach it in a way that will help them look at the world a little differently.

I thought of this recently when I realized that my daughter was coming home from school each day with new “brain teasers” to share. Like a coach who has players do warm-ups, her math teacher was sharing puzzles with her class every day, to help them think about problems before settling in to learn Math. She has joyfully been bringing home the problems for me, some of which I solved immediately, and some of which I had difficulty solving.

After teaching at a women’s college for almost twenty years, I didn’t think twice when she told me about a surgeon who said “I can’t operate on this child- he is my son” when the surgeon was not the boy’s father. Of course, the surgeon was the boy’s mother. I found myself feeling sad to realize that such a situation is still rare enough as to show up in a “brain teaser”; can’t we do better for our daughters, who might well become world class surgeons someday?

My daughter did have the answer to a puzzle that said that a man lived all alone, and, one windy and rainy night, he shut off the light. The next morning, when he woke up, he found that seven people had died. What happened? The man was supposed to be operating a light house, and shutting off the light led to boats crashing.

I sometimes begin my class in Number theory with a problem of my own. A man is staying on the fifteenth floor of a hotel, and takes the stairs down two flights. He ends up on the twelfth floor. Why? The answer is that, in most hotels, there is no thirteenth floor, so going down two flights will land him on the twelfth floor. And yes, there are lots of eyes rolling at that one.

Which all leaves me with the question; do any of my readers present games or puzzles to their classes, in an effort to get students’ brains working in preparation for learning new material? And if you do, what are the puzzles that you share?

+ -