The purpose of this investigation was to determine how students used various multiple visual and auditory external representations to develop their understanding of limiting reagents. Specifically I sought to identify the representations that were useful, and then the particular characteristics that made those representations effective in helping students create their understanding. The investigation used the Synchronized Multiple Visualizations of Chemistry (SMV Chem) program. SMV Chem allowed learners to use five external representations (4 visual, 1 auditory) of a given chemistry topic in any order or combination that they chose. The four visual external representations consisted of a real time video of a chemical reaction (macroscopic level of understanding), a computer animation of the reaction (microscopic symbolic level), a graphical representation (macroscopic symbolic level), and a text representation (verbal text level) of a mathematical problem concerning limiting reagents. Each visual external representation had an accompanying audio track (verbal auditory level) to narrate the action that occurred during the representation that could be selected or not, according to the user's choice. This module was chosen because the topic of limiting reagents as presented in this module provided students with the opportunity to explore the various levels as presented by the representations in developing their understanding of the chemistry.

Through interviews with 12 participants, several trends emerged in terms of the representations and their use. Each representation was found be helpful for creating understanding about a certain part of the overall concept of limiting reagents. Difficulties arose for the participants in terms of cognitive constraints; when cognitive functions were overloaded, due to complexity or the amount of information presented, they were not able to create an understanding. Conversely, specific combinations and aspects of the representations supported cognitive functions and the creation of an understanding. Overall, the participants felt that the use of computer visualizations was beneficial.