Abstract

This study stems from a larger study that explores students’ understanding of the concept of ten. It discusses the difficulties inherent in subtraction and multi-digit subtraction and highlights the interrelatedness of the concept of ten and place value. The current study focuses on two second-grade students whose knowledge of the subtraction algorithm seemed comparable, yet the depth of their understanding of ten was different. Clinical interviews were used to collect data and were subsequently used to make inferences about students’ understanding of ten. This study is structured into four major parts: (1) it offers a brief discussion of subtraction and its complication; (2) it gives a brief description of mathematics teachings and the concept of ten; (3) it makes a presentation of two case studies that shed light on students’ thought processes; (4) it offers insights into their understanding of the concept of ten. The findings show that this format enabled students to articulate their thought processes and exposed the delicateness of their understanding. This would not have been revealed by merely examining students’ scores and handwritten work.