Developing understanding of triangle

As children develop concepts of shape they move from a visual understanding to a property based approach to classification. In this study two cohorts, one a longitudinal study from grade 1 to 4 and the other a sample across a school from pre-school to grade 8, were asked to identify triangles. The resulting data shows errors of inclusion are greater than errors of exclusion and suggests an order in which particular properties are attended to as children learn