Technological Pedagogical Content Knowledge (TPACK) describes a significant qualification for teachers and pre-service teachers to address the integration of contemporary technological advancements into lessons that adequately reflect the subject matter for a diverse set of students. Various methods and models have been identified to develop and evaluate the TPACK of teachers and pre-service teachers. This case study aimed to enrich and deepen the descriptors of the Niess (2013) model to better assist pre-service mathematics teacher educators as they redesign their teacher education programs for developing the TPACK needed in this digital age. Data were collected from semi-structured interview forms, lesson plans, micro teaching experiences, and interviews. The study group comprised seven volunteer mathematics pre-service teachers in the final term of their undergraduate education program. Analysis of the data generated a revised model to guide the TPACK development of pre-service mathematics teachers.