Abstract
The purpose of the present study was to examine the effectiveness of an intervention package that included an action theory approach for reducing the amount of time that a youth with an intellectual disability (CA 12-2 at the start of the study) left his seat in his classroom, using a single-case design. The measure was the amount of time the boy spent in his seat. During the intervention period, the amount of time that the boy was seated greatly increased, compared to the baseline period. This result suggests that the intervention may have been effective. Possible reasons for its effectiveness are (a) that it was implemented properly, in according with the boy's actual situation, and (b) that an accurate support tool had been prepared for him. A social validity assessment indicated that the boy's parents had a positive view of the intervention procedure.
