Piaget's theory of stage structure is synonymous with discussions involving cognitive development. As with any theoretical model, researchers inevitably and rightly seek to affirm and/or contest the elements of the model presented. In this comparative study, students' performance across three hands-on engineering tasks for two distinct student cohort groups were investigated including young primary school students (aged 8 to 10) in Piaget's concrete operations; and older secondary school students (aged 15 to 18) in Piaget's formal operations stage of cognitive development. The purpose was to gain an insight into Piaget's stage structure from the perspective of the compulsory national Technologies curriculum in Australia, of which engineering is a core subject. The senior students outperformed their younger peers on all three tasks (simple, complicated and complex), with differences in abstraction and spatial inferential reasoning abilities increasing, as the task complexity increased. Although there is very limited evidence linking practical technological subjects and Piaget's cognitive development model, the findings were consistent with respect to students' abstract thinking capabilities and their cognitive development.