I promised I would tell you about the great book for school parties, so here you go!
It is called Halloween School Parties: What Do I do? by Wilhelminia Ripple ; illustrated by Heather Anderson.
It has so many great ideas- and not just Halloween. The beginning of the book gives tips about how to be an effective room mother & how to recruit other parents to help in the classroom. Many of the game and activities can be easily adapted for other themes or settings. I highly recommend this book! I got it at the library. It is also available various places online, along with her other titles.
I tried to put a picture here, but it didn't work, so you'll have to take my word for it.