Setting Goals for Student Improvement using NWEA.

Last year, in my Professional Learning Community, we set goals for student improvement, using North West Evaluation Assessment (NWEA). It was a struggle, as it was our first year of implementation. I was wondering if anyone else had used the student goal setting for student improvement. If so how did it go for you? Also did you have negative growth and if so how did you approach the student with their negative growth? As we had some students with negative growth and teachers were wondering how should they approach their students with this information?