A good or interesting question from a student can completely derail my lessons. I have tremendous difficulty saying "that's a good question about something I find interesting, but we need to talk about exponents, so hang on to it."
Instead, I say "that's a good questions, so I'll talk about it for a bit and then follow the tangents until the bell rings."
In my first two sections of Pre-Algebra today, we had and excellent lesson about the angles formed when two parallel lines are cut by a transversal. The kids were involved and good discussions were had. We talked about the reasoning behind every statement they made when I followed every answer with "how do you know?" They were willing to give their reasoning in ways that I hadn't truly seen before. It could be due to the low-entry nature of the activity and how it was more logic and vocabulary than what they traditionally think of as math, but either way, I'll take it!
Even the Math 7 classes went well today. Our work with combining like terms took longer than I had planned, but we were having excellent discussions about reasoning and representation.
"If I have 5x+2, why can't I just put those together to get 7?"
"At my house, I have 3 tomatoes and 2 plums. If I cook 2 tomatoes and my wife buys 2 more plums, what do we have?"
"1 tomato and 4 plums."
"Could I say I have 5 plums?"
"No. They are different things. You can't put them to.....oooooooooh!"
Then 8th period came in and, after doing our warm up, a girl raised her hand.
"Mr. Aion, I've always wondered. How do they build bridges?"
30 minutes later, we've watched 2 videos from OK Go and are talking about the science behind space movies.
I don't always get side-tracked, but when I do, every student in interested and I'm left wondering how I can get that level of interest during my content activities.