Description:
Previous research shows that speed is one of the most difficult in theupper grades of primary school. It is because students must take intoconsideration of two variables; distance and time. Nevertheless,Indonesian students usually learn this concept as a transmission subject and teacher more emphasizes on formal mathematics in which theconcept of speed given as “distance by time”rigorously. A sequence oflearning activities with toy cars context was designed based onstudents’ development and Realistic Mathematics Education (RME) principles which are guided reinvention, didactical phenomenology andemergent modelling. Using their own models, students are able toexplain a proportion among distance and time in speed as well therelationship of it.