By focusing on the findings from one case study, this article demonstrates a replicable individualised approach to identifying variability of ADHD symptoms across contexts at given times in a main phase and follow-up phase (situational variability) and across both phases (temporal variability) in a primary school setting. Currently we have found no studies that focus on both situational and temporal variability in the same curricular contexts. A mixed-method approach combines quantitative and qualitative research strategies. Two classroom observation schedules incorporating the DSM-IV diagnostic criteria for ADHD have been used over a two-year period to gather unique quantitative data on the variability of ADHD symptoms. Other data-gathering techniques include the use of field notes and interviews. Identification is made of contextual and curricular settings and approaches which may reduce ADHD behaviours. Such indicators may help teachers to enhance on-task behaviour in pupils with ADHD. Discussion focuses on: the delivery and organisation of the curriculum; teaching and learning styles; and grouping and support in the mainstream classroom. (Contains 3 tables and 4 figures.)