In this article, we describe one possible way to modify volume tasks in textbooks to promote conceptual understanding of the volume formula: length × width × height. From the results of previous studies regarding students' understanding of volume measurement, we identified three conceptual ideas key to understanding volume: filling three-dimensional space with equal-sized units, layer structure, and linking layer structure to the volume formula. Our examination of three popular US textbook series showed that these three conceptual ideas were not well-presented. We conclude with recommendations for one possible way to modify tasks to improve conceptually-based volume instruction.