Inaccurate mental addition and subtraction: Causes and compensation

Heirdsfield, Ann M. (2002) Inaccurate mental addition and subtraction: Causes and compensation. In Barton, B., Irwin, K. C., Pfannkuch, M., & Thomas, M. O. J. (Eds.) Mathematics Education in the South Pacific, July, Auckland, NZ.


This paper reports on a study of seven Year 3 students’ diminished performance in addition and subtraction mental computation. Although all students were identified as being inaccurate, three students used some variety of mental strategies, while the other students used only one strategy that reflected the written procedure for each of the addition and subtraction algorithms taught in the classroom. Interviews were used to identify students’ knowledge and ability with respect to number sense (including numeration, number and operations, basic facts, estimation), metacognition, affects, and memory. Two conceptual frameworks were developed, one representing the flexible mental computers, and the other representing the inflexible mental computers. These frameworks identified factors and relationships between factors that influence flexibility in these inaccurate mental computers. The frameworks were compared with a framework of an ideal mental computer. These frameworks showed that inaccuracy resulted from disconnected and deficient cognitive, metacognitive, and affective factors; and in some cases might have been affected by deficient short-term memory. It appeared that students’ choices of mental strategies resulted from different forms of compensation for varying levels of deficiencies.

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ID Code: 1151
Item Type: Conference Paper
Refereed: Yes
Keywords: mathematics education, mental computation, addition, subtraction
Subjects: Australian and New Zealand Standard Research Classification > EDUCATION (130000) > CURRICULUM AND PEDAGOGY (130200) > Mathematics and Numeracy Curriculum and Pedagogy (130208)
Divisions: Current > QUT Faculties and Divisions > Faculty of Education
Copyright Owner: Copyright 2002 (please consult author)
Deposited On: 28 Apr 2005 00:00
Last Modified: 09 Jun 2010 12:24

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