The aim of this study was to investigate the impact of instructional context on levels of attention-related behaviors among
children with ADHD and their normal developing classmates. To address the limitations in previous studies, we included a wider variety of class context conditions (i.e., different class structures and academic content types with inclusion of instructional transition periods) and a range of levels of teacher supervision. Confounding effects of academic performance on on-task behavior were additionally explored. From a methodological view, observations were taken across the whole school day on two separate days in order to capture a variety of settings. A more detailed coding allowed the measuring of not only children's overall percentage of time spent on-task but also duration of each on-task interval (i.e., on-task span). We formulated the following research questions: