Regardless of what is intended by government curriculum specifications and advised by educational experts, the ICT competencies or skills taught and learned in and out of classrooms can vary considerably. In this paper, we explore how we can investigate the perceptions that individual teachers have of ICT as a subject, and how these and other factors may influence students' learning. We report small-scale multiple case study research which examines ICT teaching as an activity system and identifies contradictions within the teaching of ICT, highlighting issues concerning the object of the curriculum, the roles of the participants and the cultures of schools. We discuss how these contradictions may be resolved and the emerging variations in the teacher's perceptions of ICT as a subject and their practice within the classroom. Finally we discuss how these variations may impact on future suggested changes to the curriculum in Wales for ICT and Computing, particularly how differences in perception and practice between teachers may impact on pupil experience and the development of the subject.