Development of an Expert Explanation: An Analysis of a Sequence of Subtraction Lessons
An expert explanation helps students understand the constraints and begin to master the difficult subtraction–with–regrouping algorithm. By studying the cognitive aspects of such expert explanations, can begin to discern the critical features of an explanation. The goals of the component were to determine the level of the students' skill in and understanding of the addition-with-regrouping algorithm and to assess the students' knowledge of the relationship between written numbers and the value. The power of using a semantic net comes from its ability to display the connected concepts even when the concepts are presents at different times. In the analyses, node–link diagrams display concepts and their connections as presented during the course of instruction. The low–ability students' performance on interviews and tests showed that they had reached a considerable level of mastery and that the earlier misconceptions were resolves, although the conceptual foundation for the skill was somewhat thin, as shown by the sparse nets and fragmented concepts.