Evaluating of Rational Number Misconception Test (RNMT) with Rasch model

A big source of Rational number misconception is the "natural number bias". This term refers to the Interference of natural number knowledge in rational numbers. The research literature points at three main aspects where natural number knowledge are inappropriately Interfered in rational numbers tasks: "density", "operations", and "size". The overall goal of this study was to assess the psychometric properties items of "natural number bias test". To achieve this goal, a comprehensive test was constructed to test 7 and 9 graders’ natural number bias. This test had 62 tasks which administered on 181 secondary school students at Kerman in a pencil-and-paper form. After of pilot administration of test, data was collected and were analyzed by item response theory modeling. Data analyzing by R software has shown acceptably fitting whit dichotomous rash model. After removing 7 Item, the test had high diagnostic value in its purpose. Results showed that a natural number bias could be found on secondary student in all three aspects. The most difficulty was for "density" items and least difficult was for "size" items. "operations" items were scattered across the Rash scale. Most students were in the top questions test scale. Researchers can choose Items for participants based on their ability.