Arrows are recognized as efficient visual elements in conveying location, direction, connection, and process because the shape is thought to have an immediate, common sense impact on viewers. However, the results of our prior quantitative study did not support the assumed effects of arrows in reading energy pyramid diagrams. The current study utilized an integrated cognitive semiotics framework and a 5-phase interview to compare the interpretations of energy pyramid diagrams with or without arrows in controlled contexts. Grade 7 students (N = 18) with 3 levels of prior knowledge were randomly assigned to an experimental group (with arrows) or a control group (without arrows). Results suggested that arrows elicited more functional interpretations and confirmed that arrows could invite thematic meanings more efficiently. However, the finding that low prior knowledge participants had difficulty interpreting thematic meanings and generated misinterpretations suggests that prior knowledge plays a role in making meaning from diagrams. Considerations of the research methods and suggestions for pedagogy are discussed.