ABSTRACT
Students are inventive. When they reach a problem they do not know how to solve, they create algorithms that get them unstuck. Often, these algorithms result in erroneous solutions. For example, in the process of learning subtraction, students often commit the following smaller-from-larger “bug” (VanLehn, 1983, 1986): https://www.w3.org/1998/Math/MathML"> 63 − 29 _ 46 https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203053270/7dc7a3d2-5ed9-4ccd-9521-1c6d516f2a03/content/math_2_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/>
