In you navigations books for Number and operations on the CD is a journal article call Two Balloons for One Dollar....it is a great article and talks about the four types of proportional reasoning problems and how to know what level kids are on. I've developed a sort of rubric that I shared with my E2t2 teachers last week....I think Tera will share it on Nov. 3. If not let me know and I will send it to you.