This week-long professional development retreat engages educators across grades K-12 in the teaching and learning of mathematics.  Participants will learn how to implement a model of math instruction based on the principles of active learning, problem solving, and student-involved assessment, regardless of which math program the school has adopted.  Participants will work collaboratively to create and analyze lessons for their grade level, and will learn how assessment is used to drive instruction and learning.  Finally, participants will analyze their current teaching practices, and create an action plan for implementing the strategies and systems learned during the retreat.  Groups are encouraged to attend and collaborate together.  All participants should bring relevant planning materials, and a laptop or tablet to access shared materials.