We analyze our method of teaching with primary historical sources within the context of theoretical frameworks for the role of history in teaching mathematics developed by Barbin, Fried, Jahnke, Jankvist, and Kjeldsen and Blomhøj, and more generally from the perspective of Sfard's theory of learning as communication. We present case studies for two of our guided student modules that are built around sequences of primary sources and are intended for learning core curricular material, one on logical implication, the other on the concept of a group. Additionally, we propose some conclusions about the advantages and challenges of using primary sources in teaching mathematics.