I enjoyed the online game of finding simple machines (I just did the
garage - I always test the sites before I post to you). Site has glossary
and teacher's guide, too.
I will eventually get this linked to my page on Art-Math-Sciecne (in a few
days):
http://www.princetonol.com/groups/iad/lessons/middle/mathsci.htm
but I wanted to get the word out to you now (this is about the time my
coworkers taught their unit on simple machines - the kids had to make a
machine in science) -- Good chance for you to come up with an
interdiscipinary unit maybe.