We invite input from teachers who have used these problems in their classrooms, and from teachers who have questions concerning how they can implement the problems in their curricula. I'm so glad to read Lisa's comments. I also think it is important to prepare students for what is coming and to teach concepts correctly as early as possible. It's frustrating to try to break bad habits that are learned in early years because the students weren't ready for a concept. For instance, many of my sixth graders come to me thinking it is impossible to subtract a bigger number from a smaller number, because the rule in elementary school was that the smaller number was always subtracted from the bigger number.
Same thing happens with division.
The students are convinced that it is impossible to divide a smaller number by a larger number because they have been given absolute rules to that effect in order for them to set up division problems correctly. I think we need to be less absolute when we teach some things so that misinformation does not come back to haunt us.