A variety of context problems, models, schemas, diagrams, and symbols can support the development of progressive mathematization gradually from intuitive, informal, context-bound notions towards more formal mathematical concepts. c. Selfreliance: students’ own constructions and strategies. It is assumed that what students do in the learning processes is meaningful to them. Students are given the freedom to come up with their own construction and strategies in solving mathematical problems. d. Interactivity. The learning process is part of an interactive instruction where individual work is combined with consulting fellow students, group discussion, class discussion, presentation of one’s own strategies, evaluation of various strategies on various levels and explanation by the teacher. Hence, students can learn from each other either in groups or in whole-class discussion. e. Intertwinement. It is important to consider an instructional sequence and its relation to other related topics.