Using An Unusual Task to Investigate Elementary School Teachers’ Mathe-matical -Task Knowledge and ‎Common Content Knowledge of Fraction Con-cept in Tehran Province

This research was conducted with the aim of ‎investigating ‎Mathematical-Task Knowledge and Common Content Knowledge ‎of ‎elementary School teachers of fraction concept in Tehran province. The method of this study was ‎descriptive-survey method, its ‎statistical ‎population included the elementary School teachers in Tehran province ‎in the academic year 1397-‎‎1398 and its sample were 137 ‎people ‎selected by multi-stage cluster sampling method. In this study, a researcher-made test consisting of an unusual two-part task was used to examine the Mathematical-Task Knowledge and Common Content Knowledge ‎of ‎elementary teachers regarding the fraction concept.‎ The results of the study revealed that teachers do not have ‎suitable Mathematical-Task Knowledge and Common Content Knowledge of the fraction concept (part-whole sub-construct). ‎The overemphasis on part-whole sub-construct, lack of attention ‎to all aspects of part-whole sub-construct of fraction, and lack of ‎balanced attention to other sub-constructs of fraction concept in the ‎educational content of teachers and students can be part of the ‎possible causes of this weakness. Therefore, balancing the various ‎sub-constructs of fraction concept and disengagement from the part-whole approach in the educational content of teachers and students and improving elementary teachers' Common Content Knowledge and Mathematical-Task Knowledge through courses and workshops are the suggestions of this study.