The mental model theory (MMT) proposes that reasoners mentally construct iconic representations of the information they have processed (Johnson-Laird, 2020). This study focuses on the mental model theory to explore the effect of working memory on reasoning, how mental models are represented internally, and how these features of reasoning vary across developmental stages. We referred to Demiddele et al.’s (2019) methods as the foundation of our analysis of the mental model theory in schoolchildren. The main finding of this study was that when note-taking is available, participants spontaneously draw iconic representations of the information consistent with MMT. Their performances varied with and without notes, with participants generally scoring more points when they took notes. In our replication, we attempted to recreate the results of the original study through an in-depth analysis of the statistical models utilized that assessed the implications and the application of the mental model theory in schoolchildren. In our extension, we discovered that when taking into consideration the number of notes taken by the children working through the various problem types, the results yielded another perspective with regards to the mental model theory, essentially showing that note-taking for some problems was not beneficial. The trends also aligned with the original study when considering the groups that were allowed to take notes compared to those that weren't. The findings of this study will allow future researchers to build upon the mental model theory and apply it in other areas of study.