Grounded in a constructionist paradigm, this study examined elementary school teachers' learning while creating technology-rich instructional materials. Sixteen teachers at an elementary school were interviewed about their experience. Using the components of Technological Pedagogical and Content Knowledge as an analytical framework, inductive qualitative analysis indicated that these professional learning activities led to teachers' growth primarily in technological knowledge, technological pedagogical knowledge and content knowledge. These findings as well as implications for designing professional learning activities for teachers are also shared.