Mobile technology is ubiquitous and diverse and permeates many aspects of daily life at home, during leisure activities, and in public spaces. The study presented here is of two sixth grade classes in Michigan, USA and two seventh grade classes in Norway. The students and the teachers in these four classrooms were equipped with mobile technologies (PDAs). We found that the students' PDA-mediated actions in the classroom were not exclusively used for the tasks and activities set by the teacher, but that the students also used the PDAs on their own initiative--so-called "off-task" activities. We analyze the findings by reconsidering off-task activities from a sociocultural perspective.