Four elementary school instructors offer insights into their classrooms, their unique professional roles, and their leadership approaches as they reflect on their journey to advance teacher and student mathematics learning. They note a "teacher leader" serves as an example to other educators and strives to impact student learning; consistently assesses and seeks evidence of student success; and is a learner, improviser, and innovator. These elementary school instructors all speak of the training they received via the Leadership Institute for Teachers (LIFT) partnership between a university and public school districts. They highlight the LIFT program that provided educational experiences that advanced their professional growth to support all students' learning. They participated in six semesters of rigorous course work designed and team taught by mathematicians and math educators. The diversity of K-grade 12 LIFT teachers offered opportunities for thinking about mathematics through research-based learning progressions and they are using these learned lessons in their individual classrooms. They agreed that to engage in mathematical reasoning to solve simple and complex problems resulted in their students having a solid understanding of the concepts and being able to explain their rationale with excellent articulation, using mathematical terms to do so. Student achievement scores were exceptional, and they were developing Common Core State Standards for Mathematics (CCSSM) practices that supported their continued learning.