Mathematics and science are often combined in early childhood education programs into a single methods course. This can lead to an integrated view of the two, thus neglecting their conceptual, procedural, and epistemological differences. To promote their foundational integrities, we, one mathematics and one science educator, collaborated on teaching an amalgamated course. Our impetus was the need to develop mutual ability to instruct the course independently. In this paper, we reflect on and discuss the context of our collaboration, from which emerged a conceptualization of co-teaching that emphasizes the importance of context for motivating and understanding its nature. (Contains 1 figure.)