This document outlines a professional development session for teachers on implementing changes to the teaching of mathematics at RPPS. It introduces the "Mathematician's Model" which involves dividing math lessons into four "toolbox lessons" focusing on developing problem solving strategies and mental math skills, and two "Be a Mathematician" lessons using rich, open-ended tasks. Examples of effective rich tasks are provided, emphasizing that they should be problem-based, inquiry-driven, collaborative, and engage students through hands-on experiences. The session celebrates mathematicians as role models and quotes Paul Halmos emphasizing experimentation and problem-solving over memorization of facts.