This topic (bell work) comes up a couple times a year on the list serves....
Milisa has posted a book to Art Education 2.0 that she uses in her classes.
From Milisa:
I have been using a great book in my digital photography classroom called
" Caffeine for the Creative Mind" by Stefan Mumaw and Wendy Lee
Oldfield. I highly recommend it. It has "250 creative design
excercises to wake up your mind." I had been looking for similar books
to use as daily bell work (required by my school) this is a great
little book containing critical and creative thinking, attention
getting, problem solving exercises for students that can be adapted as
needed.
To find out more about Art Education 2.0 - check out:
http://arted20.ning.com/
Registration is free.... you will get to see stuff like this first
hand. I don't post all of the good stuff here.