Despite the commitment to promote equity and excellence in education, significant gaps remain in understanding the numeracy development of students with special needs. How these students become competent with fraction ideas, essential skills needed to become numerate and learn higher mathematics, is unclear. Most studies rely on an experimental design to teach basic skills through drill and practice, very few focus on conceptual understanding, learning more complex mathematics, or researching teacher professional development. This book reports the learning journey of three middle school teachers and their students with special needs. Using design based research method, a range of activities and instructional games were designed to teach for conceptual understanding. Analysis of classroom interactions helped identify the connection between teacher knowledge, learning activities, and student learning, and in turn, contribute to our understanding of how to help these students to become numerate.