Correlation between time of day and student behavior

Ok now that I sound all academic, here's a little slice of my day... notes from the 5 high school classes I taught today

11:00 am Students arrive before me and have designated someone to retrieve the key, unlock the classroom and turn the lights on. Students are quite attentive but start to lose focus as lunch draws nearer.

1:15 pm Students are obviously still groggy from their afternoon nap. Regular greetings get little to no response. Icebreaker has moderate effect on class energy level once students manage to get up out of their seats.

2:15 pm Students answer greetings with grunts vaguely resembling language, but appear slightly more alert than the previous class except for two sleepers. Have brought energy to acceptable levels by the end of class.

3:15 pm Chatting giggling girls arrive five minutes before the class ready to engage, and asking to turn on the air conditioner since they just had P.E. Students jump right into class and move through activities faster than previous two classes.

4:30 pm Students arrive late because of school-wide dancing session during the break, which has a similar effect as the P.E. class though its benefits do not last as long. The almost-time-to-go-home lull sets in by the halfway point.