Pedagogical and epistemological criteria of science teachers to guide their thoughts and educational activities are evident through the recognition of the positions assumed, as expressions of subjectivity teaching. Teachers in this discourse, reveal a state of confusion over terminology and explanatory interpretive frameworks that support their views and assessment practices, which appear as traditional and innovative, without distinction. Such interventions express the reduced effectiveness of teacher training process changes promoted, and conversely, a series of embarrassments in making pedagogical decisions. © Universidad Nacional Autónoma de México.