In this worked example we present ongoing research in the realization and evaluation of a new mixed-reality learning environment called SMALLab. Within SMALLab, students interact in real time with each other and with dynamic visual, textual, physical, and sonic media through full-body 3D movements and gestures. The environment fosters embodied and multimodal learning in a manner that brings together contemporary research in the learning sciences and human-computer interaction. The need for new approaches to science education and a recent study of SMALLab learning in a high school physics classroom are presented. We describe a game-based scenario for learning about constant velocity. We present an assessment framework that integrates a variety of measures to provide a broad view of SMALLab-facilitated learning in a formal school context. The primary focus of this study is to explore the impact of SMALLab learning on representational fluency. Results suggest that embodied activity in SMALLab scenarios with multiple representations (i.e., representing physics constructs graphically, algebraically, verbally, etc.) is strongly related to better performance on more traditional measures of representational fluency. The current study is one component of a longitudinal examination of the efficacy of embodied SMALLab learning.