Two phenomena related to the quality of student responses in regard to items used in a testing situation are involved in the construction of a pupil response model. The underlying phenomenon which defines the individual's cognitive limits is termed the hypothetical cognitive structure (HCS). The second phenomenon, which is a function of not only the HCS but also of experience in a content area, learning opportunities, and a person's past and present motivation, is termed the structure of the learned outcome (SOLO). The report looks at the optimum achievement of the HCS at the different developmental levels, then relates these to the SOLO levels. The reponse model is applied and summarized in a profile of response characteristics. Examples of pupils' responses in two particular elementary mathematical items are presented with commentary. Among the conclusions, it is stated that focusing the educator's attention on response levels and their structure has major implications for the classroom educational process. (MP)