摘要：The purpose of this research is to determine mental computation strategies used to make addition-subtraction by fifth grade students. Also, the students’ choices for the ideal mental computation strategies are examined in this research. The research designed according to case study of qualitative research models was carried out in the fall semester of 2014-2015 academic terms. The research was conducted with 33 fifth grade students, including 16 boys and 17 girls, studying in a state middle school. The research data were collected with a task based semi-structured interview protocol developed by researchers. Qualitative data obtained from the interview protocol were examined by descriptive analysis according to existing mental computation strategies of addition-subtraction. According to the results of the research students used at most “Adding by dividing into decimal and unity” and at least “Dividing based ten” in addition. Also, students used at most “Subtracting ten by ten” and at least “Subtracting by dividing into decimal and unity” in subtraction. Nevertheless, most students did not use any strategy for addition-subtraction and answer the questions correctly. When the students’ assessments for the favoured mental computation strategies examined, the students preferred the strategies that they use substantially.
关键词：Mental Computation; Strategy; Middle School Students; Mathematics Education
