Every few years you get really lucky. I work at a high school. I am a science teacher and I teach chemistry in higher levels. This year I teach one of the two year four classes (15-16 years) that study chemistry. My students love science and they can not get enough of it. We go over the material that I am supposed to teach and they can not get enough of it. They want to know about atoms and molecules and how they are formed. You talk about diamond to explain about Carbon and they want to know about graphite because that is carbon too. They see some notes for year 6 on the white board and want to now what they mean. They would like to finish the book straight away and move on to the next book. I know that working (and especially teaching) is supposed to cost energy, but this group just makes my day. Can you see why I feel lucky?