This paper presents the development and structure of indigenous Nahua teachers' ideas about mixing colors, as well their ideas about colors derived from their traditions. For the scientific school knowledge, teachers answered two questionnaires and an interview regarding knowledge from their culture; they were interviewed outside school. This represents two different types of knowledge that were analyzed with a distinct methodology. Ideas referring to scientific knowledge were analyzed using the partial possible model, which states that the inferences and explanations used to describe a subject consist of constricting ideas, rules of correspondence and a set of phenomenological inferences about processes. With those components, we developed models to describe conceptions about mixing colors. The cultural analysis involves how colors are related to a Nahua cultural environment through stories and tales that add properties to colors depending on their effects on people. For the analysis, we used a model based on non-sequential functional mechanisms. In the school context, the results showed that teachers change from a conception that focuses on colors as entities that do not change and as properties of the object to the idea that color represents a quality of substances or objects that can be modified by mixing them. The cultural context analysis showed almost no influence from community cultural aspects over the teachers' conceptions about colors. We conclude that teachers generate independent constructions between school and cultural knowledge.