the dance the next night

Probably still play the football game, since it involved another school and would be much more difficult to reschedule. Dance would probably be postponed a week or 2, to give everyone a chance to grieve. Still would want to have it eventually but everyone would have still been in a state of shock, and there would have been major safety concerns for the kids.

Then again I'm basing this on how a school would handle this today. In the 70's they may have gone ahead with it anyways, and good number of people might not have even heard about what happened.

Do you think Paul played the grieving boyfriend angle to score an even hotter date?

Jamie Lee Curtis just discussed this in a recent interview for the new movie. She talks how Laurie probably only took a few days off of school and went back as her parents would have had mid-west mentality of shake it off and move on. I assume that they do discuss some of this is the new movie

Or maybe the dance changed its theme to something having to do with mass murder!

They'd probably turn it into a vigil.