The main purpose of this research was to determine three- to six-year-old pre-schoolers' recognition of basic geometric shapes, the criteria they use to distinguish members of a shape class and whether or not those criteria change in relation to age. Participants were 100 children aged three to six. Data were gathered from individual interviews conducted with participants. The results of this study indicate that pre-school children fail to distinguish circle, square, triangle and rectangle and recognize atypical examples which differ due to orientation, aspect ratio, skewness and size. Furthermore, children in this period are capable of attending to both defining and non-defining attributes while classifying, but they mostly rely on non-defining attributes.