This study aimed to evaluate the effectiveness of the Prime Factors Chart (PFC) as an alternative teaching material, which was developed for teaching the concepts within the "factors and multiples" unit in the middle school mathematics curriculum. Twelve middle school mathematics teachers used the PFC to teach concepts, such as prime number, prime factor, the highest common factor, and the least common multiple, relatively prime numbers, factors, and multiples during face-to-face education in 4 lesson hours. The teachers and their students (n=90) evaluated the PFC based on the framework of the principles of material development. The participant teachers' and students' opinions indicated that the PFC is simple and understandable, suitable for the learning objectives and outcomes, suitable for the developmental characteristics of the students, and simple enough to be used by students as well as teachers.