Answers to questions in a grade 11 physics examination were analyzed to provide information on the cognitive development of Australian science students. Data from questions concerned with volume, mass and weight, levers and proportion, speed and velocity, acceleration and relative speed are compared with Piaget's findings: many of the students do not appear to have attained formal operations, despite the fact that the physics students are a selected, above-average ability group. Implications for teachers of science at lower levels are briefly discussed. (AL)