I saw in a post somewhere about letting kids put their names on glass windows as a behavior incentive. I bet my students would love this. What kind of marker/writing utensil would work on glass and come off easily with a bit of windex?
Dry Erase Markers also work nice on windows and come off super easy. Personally I hate window crayons as they get globby and are very hard to write with, but I have used dry erase markers and they were very easy to clean off with just a little cleaner and paper towel after about 8 weeks.
I love dry erase for this - in my last classroom, I had a window dividing my classroom from the computer room. When part of my class was on computers and part in my classroom I loved it because I could use my expo markers to write information for the computer students on the windows. This practice also helped me master the art of backwards writing!!
I had left it up for 8 weeks! It was for a summer enrichment class and I had a different group each week, so I never had to change my decor since it was new to each group.
The Crayola Window Crayons are fantastic!! They come off with water and they show up better than the markers.
Last year I used the glass markers (for cars) they sell at Walmart, Party Stores, & Office Max. It stayed on the whole year & at the end I had students wipe it off with water & paper towels. I totally am doing it again next year!