Objective: Explicit instructions to students to use the index finger to trace out specified elements of mathematics worked examples have been shown to improve mathematics learning outcomes; however, there is limited research on whether the magnitude of tracing actions impacts these outcomes. Method: Using an experimental design, 34 adults were randomly allocated to an experimental (tracing out larger ellipses) or control (tracing out smaller ellipses) condition. We hypothesised explicit instructions to make larger tracing actions on the surface of worked examples on a mental mathematics skill would support learning more than making smaller tracing actions. Video analysis established the two conditions differed in distance traced in the expected direction. Results: Contrary to hypotheses, making larger tracing actions did not result in better post-lesson problem-solving. Instead, an aptitude-treatment interaction was established between multiplication expertise and experimental condition, with less expert students in particular solving more similar post-test problems after making smaller tracing actions. This interaction may reflect a split-attention effect generated by experimental materials. Conclusions: Findings suggest there needs to be close consideration of how instructions to trace lesson elements are designed, so that visual processing following the index finger supports rather than hinders learning. Directions for future research are discussed.