judgement call...

I had to give a pretty important lecture today in Physics class - introducing the basic equations of accelerated motion. It's not incredibly difficult stuff, but it's hard enough that some students don't get it right away (or at all). And if you don't get these basic ideas of velocity and acceleration down during the first few weeks, NOTHING else makes sense... projectile motion doesn't make sense, F=ma doesn't make sense... and students never recover.

I was very careful about putting together the lecture so I wouldn't stumble over any math at any point. I think I went just a tiny bit too fast, but I think it went pretty well. But when I looked at my watch after solving a few sample problems, I saw that there were still 20 minutes left in class. I looked around at the students, who were still hanging in there, but just barely. That's when I realized I had a decision to make. The decision...? "Ok, you know what...? You guys are FULL. Go away, and I'll see you next week."

Part of good teaching... knowing when to quit.