The turning point for all the kiddos came when I posed the following questions to them:
How many difenwarps is 2.931 yipyaps if there are 436.9 difenwarps per yipyap?
After a heated argument about the pronunciation of "difenwarp" (which, mind you, included them informing me that my pronunciation was wrong despite the fact that I invented the word), even the fast kids started to realize that their intuition wasn't always going to serve them in unfamiliar territory.
I decided to introduce KWL charts to them as a means of gathering information. I always liked the idea of them, but for other subjects....kids want to know about their bodies or wars. Kids are less likely to want to know about combining like terms. Here's a sample of the one I used with them:
Ohhhh happy day! Seems like most of the resources I could find were high school chemistry labs. I'm thinking next year maybe we bake...they have to convert, they get a delicious baked good as a reward! Any other good ideas for dimensional analysis?