Background: Understanding the properties of sound is difficult for students across all grade levels and even preservice elementary teachers (PSETs). Because of their abstract nature, there are challenges interpreting common features of sound waves. Purpose: The goal of this study is to understand pre-service elementary teachers' (PSETs) understanding of the properties of sound waves, specifically frequency, wavelength, and amplitude. Sample: We had 59 PSETs from an elementary methods science course learn about the properties of sound in small groups through a Web-based interface. Design and Methods: After they used a simulation model of an oscilloscope, we analyzed PSETs' responses to three prompts assessing their understanding of the relationships among frequency, wavelength, and amplitude. They were asked to construct explanations for the changing frequency in an oscilloscope, how adding water to a container changes the pitch of sound and how the frequency changes in a water-based xylophone. We used the Knowledge Integration (KI) framework to understand how PSETs reasoned through properties of sound waves. Results: Our findings delineated three levels of explainers that PSET groups divided into. After the unit PSETs' overall understanding of sound waves became more normative, particularly around ideas of frequency and wavelength. Conclusions: The merging of science and technology played a crucial role in promoting meaningful learning for PSETs. Implications of using technology-enhanced units in supporting PSETs' understanding of sound waves are discussed.