摘要：The cognitive obstacle is a thinking barrier of pre-service teachers caused by less meaningful learning and the difficult nature of fraction material. The pre-service teachers’ cognitive obstacle measurement is done by giving negative fraction questions that contradict positive fractions. This research objective is to develop an instrument that can measure cognitive obstacles based on mental mechanism stages. This development research uses three stages of 4D development: defining, designing, and developing. The research participants were 71 preservice teachers from two different universities in Malang, Indonesia. The research findings show that questions of a negative fraction have a high level of validity in measuring the cognitive obstacle of preservice teachers. Triangulation is recommended for further research related to cognitive obstacles that arise when solving fraction problems of negative nu mbers.
