Interaction among students, between teacher and student, and among teachers is important in the process of creating mathematical knowledge. Dialogue with students enables the teacher to explore students' understandings and to offer suggestions about procedures. Discussions, whether whole-class or small-group, provide the opportunity for students to share insights and to identify misunderstandings. Teachers must listen to students and carefully use the knowledge they gain to help students craft their own approach to the mathematics.

  Many instructional strategies are possible: group work, whole-class instruction, or individual work. Students can engage in projects, make reports, or solve problems using manipulatives or technology. Although the teacher's guide for each unit makes suggestions about various appropriate methods, teachers are free to choose the method that works best for them. The teacher's decision depends on the classroom atmosphere, as well as on the mathematical content of the unit. The most important thing for the students is that they are doing mathematics in a variety of ways.