Background: The study focused on children with hearing disabilities, which was significant as almost 9 million children in sub-Saharan Africa, including Namibia, had hearing disabilities. The problem was the lack of prior research on the effects of assistive technology (AT) in primary education for the Deaf in Namibia, for guiding Namibian special primary schools and educators. Aim: The aim was to investigate the effects of Constructivism-led AT on the teaching and learning of learners who were deaf, in a mathematics class at a rural special primary school. Setting: The study involved Grade three children who were deaf. Grade 3 is where children learn to build and understand foundational and basic mathematical concepts, such as counting, which they require for subsequent mathematics learning and practice. Methods: The study was a mixed-methods study comprising a quantitative experiment and qualitative interviews. Results: The findings suggested that the Constructivism-led AT may have had a positive effect on the children's multiplication and division achievement, but not on their addition and subtraction achievement. The teachers were positive about the Constructivism-led AT and indicated that it supported collaborating, cooperating, exploring, self-assessing, learning from errors, seeking knowledge independently, self-regulating, self-reflecting, metacognitive thinking and being self-aware. Conclusion: For school management and teachers of children who are deaf, the study offered an intervention for potentially improving teaching and their learners' mathematics achievement. In addition, the study provided valuable evidence for policymakers about integrating technology for effective learning environments.