**3. Statement of the problems**

Implementation of mathematics instruction based on science using didactical phenomenol‐ ogy approach is asking the question "Does the teaching material of mathematics using sci‐ ence‐based didactical phenomenology approach effect positively to the students' cognitive abilities?" This formulation was translated into a number of formulations more specifically as follows: (a) How is the prototype mathematics learning using science‐based didactical phe‐ nomenology approach? (b) How does the implementation process of learning mathematics using science‐based didactical phenomenology approach? (c) What was the students' reaction to the teaching materials? These questions are answered by designing instructional materials, which are prepared in the science‐laboratory and implementing them in the real classroom.
