Considerable work over many years has explored the contribution technology can make to science learning, at all levels of education. In the school sector, historically this has focused on the use of fixed, desktop-based or semi-mobile laptop systems for purposes such as experiment data collection or analysis, or as a means of engaging or motivating interest in science. However, the advent of mobile devices such as iPads supported by a huge array of low or no cost apps, means that new opportunities are becoming available for teachers to explore how these resources may be useful for supporting "hands on" science learning. This article reports outcomes from a study of primary (elementary) school students' use of a series of apps integrated with practical science activities, in a topic exploring Energy concepts. It used an innovative display capture tool to examine how the students used the apps and features of their iPads to scaffold their practical work at different stages during the experiments. Results identify device functions and app-based scaffolds that assisted these students to structure their experiments, understand procedures, think about the influence of variables and communicate and share outcomes. However, they also discovered limitations in the apps' ability to support conceptual knowledge development, identifying the critical role of teachers and the importance of task structure and design to ensuring conceptual knowledge objectives are met.