Gesturally controlled information and communication technologies, such as tablet devices, are becoming increasingly popular tools for teaching and learning. Based on the theoretical frameworks of cognitive load and embodied cognition, this study investigated the impact of explicit instructions to trace out elements of tablet-based worked examples on mathematical problem-solving. Participants were 61 primary school children (8-11 years), who studied worked examples on an iPad either by tracing temperature graphs with their index finger or without such tracing. Results confirmed the main hypothesis that finger tracing as a form of biologically primary knowledge would support the construction of biologically secondary knowledge needed to understand temperature graphs. Children in the tracing condition achieved higher performance on transfer test questions. The theoretical and practical implications of the results are discussed.