For years students would say to me, "When are we ever gonna use this stuff?", and in a CPM classroom, I never hear this any more. Lessons are built around applications rather than drill. These are activities that stick with students, and help develop understanding.
It is never necessary for me to find "supplemental" practice materials. I keep in mind that "mastery takes time," and if students "don't get it" the first time, spaced practice brings it back. This reoccurring exposure helps the student develop a conceptual understanding.
The opportunity to talk about problems during team tests has been exciting for students. The talk is about mathematics, and hearing students talk and explain to each other reinforces their learning.
Creating their own toolkits/learning logs has been a good way for students to organize their learning. The fact that these study notes can be used on a test helps solidify their learning and removes the "fear" of not remembering pieces of information. Once their level of confidence and mastery with the mathematics grows, it is refreshing to see students wean themselves from the tool kit.