I agree, it was confusing for my students. Totally in agreement - it works really well for helping to explain how having a well-defined problem helps in the problem solving process - after evaluating, you have to make new definitions and goals.
This is for a sixth grade class, and we only have forty minutes at a time. I took one class to do the first two problems and a whole class to do this third problem. Next class we evaluate, discuss, and do the reflection as a summative - but I'm not going to make sure everything's perfect.
Yesterday when I tried this with my first class, they had so much trouble creating the criteria in small groups. Today for my second class, instead, we created criteria and goals as a whole class. I then used the criteria for my third and fourth classes and this definitely worked the best. I then had the kids work individually on making the plan. I attached an example of what we came up with for the criteria. (I projected it on the board and they wrote it on their worksheets).
Next year I'll just give them the criteria to start off with. I know this removes some of the confusion with the "Definition" but honestly, with sixth graders, there's enough confusion already so there's plenty to discuss afterwards