ABSTRACT
Subtraction involving negative integers is known as one of the biggest problems for students. The number line and the neutralization model have been used very extensively for several decades in introducing integer addition and subtraction. While they have been proven helpful for integer addition, problems remain for integer subtraction. Therefore, this paper aims to investigate how an alternative model, namely the ‘Neutralization on a Number Line’ (NNL) model together with the ‘two-color number card game’ context, can be used in a classroom to help students develop a meaning of integer addition and subtraction. Design research methodology was used in this study by conducting three phases: first, designing a Hypothetical Learning Trajectory (HLT), second, trying out the HLT in a classroom, and third, analyzing how the learning process took place as well as how students developed during the lessons. Students’ responses and performances were described and the HLT was compared to the actual learning process. The results show that the use of context and the NNL model could give meaning to students that subtracting a negative means adding a positive and subtracting a positive from a negative means adding two negatives.
