Lärares arbete med subtraktion i årskurs F-3 : En kvalitativ studie av strategier, didaktiska val och utmaningar

Sammanfattning

The purpose of this study is to contribute knowledge about how teachers in grades F–3 teach subtraction. The study focuses on the strategies taught, how teachers justify their pedagogical choices, and the challenges they perceive that students encounter. The study is based on national and international reports showing declining mathematics achievement and indicating that Swedish students experience greater difficulties with subtraction than with addition. The theoretical framework used is Pedagogical Content Knowledge (PCK), which is applied to analyze how teachers make mathematical content comprehensible to students. The study adopts a qualitative approach based on semi-structured interviews with 11 certified teachers. The data gathered were analyzed using thematic analysis. The results indicate that teachers use a wide range of strategies, ranging from mental strategies such as "thinking addition," "making ten," and "neighbor numbers," to structural strategies such as place value decomposition and written algorithms. The pedagogical choices are primarily motivated by the importance of using concrete materials such as Numicon and number lines, as well as collaborative learning methods such as the APE model. The main challenges identified for students include understanding subtraction as difference, difficulties with crossing tens and regrouping in written calculations. Keywords: Subtraction, strategies, pedagogical choices, challenges, Pedagogical Content Knowledge (PCK).