Using the intuitive rule more A-more B for predicting and analysing students' solutions in geometry

This article discusses the role that the intuitive rule more A-more B may play in predicting and in analysing students' solutions to geometrical tasks. In this study 289 students, K to 11th grade, compared the sum of lengths of several sides of given polygons with the sum of lengths of their remaining sides. All problems were presented in 'a specific' way via a given story, which was accompanied by a drawing that served as a visual clue to the correct answer. However, most participants gave incorrect answers. They compared, for instance, the length of the sum of two sides in a pentagon with the sum of the remaining three sides. In these cases, students tended to claim that the sum of the larger number of sides (three sides in a pentagon) was larger than the sum of the smaller number of the remaining sides (the other two sides of the pentagon). These results are in line with the intuitive rule: more A-more B.