As a Phillies fan, there's a lot to like about getting Cliff Lee back. As a baseball fan, perhaps the best part is the chaos it causes. Lee was to be the big prize for either the Yankees or the Rangers, but they both knew that one of them would lose out, so I'm sure each of them had a Plan B. But I'm pretty sure they never expected to both have to use their Plan B. There's a cascading effect that will ripple through every team's offseason in unexpected way, which will absolutely make it all more fun to watch.

I always find this kind of thing appealing. One of the reasons I like teaching is the potential for chaos. I know that in a formal lecture situation, you can plan down to the minute what you want to say and present. This has no appeal to me. I love the give and take about ideas, mathematical or otherwise. And who better to provide chaos than a bunch of teenagers? And finding the sweet spot where order and entropy are in perfect balance is always my goal.

Chaos makes you think on your feet, to be ready to react, respond, and advance based on whatever just happened. It's a lot like improvisation. In improv, the first rule is that whatever somebody says or does is a gift and that you accept it and give something in return. You never reject it, even if it's funny. So in a math class, if somebody calls out 7 when the answer should be the square root of 11, the proper response is never "No," it's "So how did you get that?" One is a dead end. The other is a journey. And the best part of journeys is the unexpected stuff you run into along the way.

One of the most fun parts of my last cross country drives was when my wife and I were driving through west Texas, which is very big and very flat. It was getting dusky and we decided to cut a corner on a back road. We were cruising along when suddenly, up ahead, we saw a cow standing perfectly in the middle of the road. We were at least 25 miles down this road, there were muddy ditches on both side of the road and nothing else around, and there was no way I was going to try to squeeze the minivan around the cow, so we stopped. We honked the horn a couple of times, as if a cow would know what that means. I love cows but they are unbelievably stupid, especially about motor vehicle courtesy.

So we got out of the car. It was getting dark and a full moon was rising. It was quiet and desolate and beautiful in a barren sort of way (which is an exquisite sort of beauty if you're open to it). Just us, the car, the moon and the cow. And after about 15 minutes, the cow moved. I was going to write, 'decided to move,' but I'm pretty sure that cows never decide anything. They just do. And we were on our way, and I still remember it 25 years later.

Maybe a math class isn't as memorable as that, but when I walk out of the room at the end of the period, what I'm thinking about is never the planned part of the lesson, it's the unplanned parts and all the discussions that sprung from them.