The use of technological resources has the potential to make viable new and less traditional methodologies of teaching that take into account student differences. Blended learning can be a way to rethink classes so that students have more freedom in their processes of learning. The goal of this article is to understand a blended learning environment from the perspective of complex systems. We observed the classroom as a complex unit emerging from collective class member interactions. Data from one of two mathematics classes of first year high school students, in São Paulo, Brazil were used in this article. The results suggested that a high school blended learning environment, when seen as a complex system, not only frees students to make personal meaning in their learning processes, but it also provides for collective learning in virtual and face-to-face groups. Features of online discussion groups contributed to the teachers' knowledge about the collective learning, providing them valuable information for formative assessment and pedagogical actions. The blended learning environment seen from a complexity perspective provided evidence that such classrooms demand a different relationship between the teacher, the learner, and the curriculum than relationships observed in the traditional class.