Graphical representations of geometrical objects from high school textbooks are categorized according to the implicit conventions underlying their display. The fact that specific illustrations can lead to students' misconceptions about geometric objects is analyzed in relationship to the principle of parallel projection with implications for the…

High school students (N=213) of various ability levels enrolled in first-year algebra classes were presented lessons concerning geometry concepts. The lessons were varied according to the degree of complexity of the examples that were presented. Students then were tested over their understanding of the concepts. The test questions ranged from…