I used to dream that I was sitting in my history classroom in school, and in this dream I would be sitting there before the lesson started and before the teacher turns up, and suddenly I'd realise I hadn't done my homework.
This dream would strike terror into my heart, sitting there waiting for the inevitable row that was coming my way (but I'd always wake up before that happened).
It's no coincidence that my history teacher's surname was an anagram of Dragon
What's funny is I only stopped having that dream about a year or two ago, and I left school 6 years ago!
I used to dream that I was getting chased by a giant dog in a revolving door as well, with the dog being in the compartment behind me, with no exit. That had nothing on the dream above though.