The purpose of this study is to use a comparative approach to scrutinize the common assumption that certain school science activities are theoretical and therefore particularly suited for engaging students with scientific ideas, whereas others are practical and, thus, not equally conducive to engagement with scientific ideas. We compared two school science activities, one (laboratory work) that is commonly regarded as focusing attention on artefacts that may distract students from central science concepts and the other (concept mapping) that is thought to make students focus directly on these concepts. We observed students in either a laboratory activity about real galvanic cells or a concept-mapping activity about idealized galvanic cells. We used a practical epistemology analysis to compare the two activities regarding students' actions towards scientific ideas and artefacts. The comparison revealed that the two activities, despite their alleged differences along the theory-practice scale, primarily resulted in similar student actions. For instance, in both activities, students interacted extensively with artefacts and, to a lesser extent, with scientific ideas. However, only occasionally did students establish any explicit continuity between artefacts and scientific ideas. The findings indicate that some of the problems commonly considered to be unique for school science practical work may indeed be a feature of school science activities more generally.