Oh man. I really blew it, this time. I should start by letting you know that I teach five of the same class in a row. It's physical science after physical science after physical science after physical science after physical science. By the fifth class, I'm lucky if I remember if I even gave an introduction or took attendance. The monotony can be overwhelming sometimes, but it definitely gives me a chance to think about what is working and what is not - by the time fifth hour rolls around, the lecture has been perfected (except for my incessant "have I already talked about ____?" "Have I told you about ____ yet?"). Well, things didn't go so smoothly today. Yesterday, I had some time management issues in fourth hour. We didn't cover how to write molecular formulas. Well, today I was supposed to cover that lil bit so that the students could prepare for their test, which is conveniently on Monday. For some reason I was convinced that I ran short in fifth hour instead. So fifth hour comes along and I tell them that we need to cover molecular formulas since we didn't get to it. They immediately recognize what I'm writing on the board and say, "We covered that yesterday!!!" In my mind, time stood still for a brief moment as I put two and two together and realized that fourth hour will have to take the test without this vital knowledge. I hope they figure it out on their own! Unfortunately, I know this won't be the case for every students. Argh. How to prevent this from happening again?