Reform efforts in science education have aimed at fostering scientific literacy by helping learners meaningfully engage in scientific practices to make sense of the world. In this paper, we report on our second year of unit implementation that has investigated 34 fifth grade students' (10-year-olds) learning about evaporation and condensation through scientific modeling in the USA. We discuss how students who engaged in modeling constructed explanations of evaporation and condensation, considered empirical evidence when constructing their models, and used models to predict other phenomena. We constructed a coding scheme based on an iterative process and qualitatively analyzed assessment items, interview questions, and classroom videos in order to find out what students learned through modeling. The results of our empirical work indicate that students made significant progress in constructing models that convey unobservable characteristics of molecular mechanisms or processes. They also made progress in using models as tools consistent with evidence and using models to predict other phenomena, but the progress was to a less sophisticated level. We theorize that some aspects of modeling practice are more aligned with typical school norms and practices than others--enabling some aspects to be more readily appropriated than others. We conclude the manuscript with ways to capitalize on the successes of this practice and to address challenges that could be taken to help improve students' understanding of science through engagement in scientific modeling.