This study elaborates on the pivotal roles of mathematical and statistical models in data-driven predictions in an integrated STEM context using the case of Year 4 students: (?) "a descriptive means" to describe the features of trends and variability of data and (?) "an explanatory means" to explain causal relationships behind data. These roles are linked to models in other STEM subjects (i.e., prototypes and scientific models) and the application and development of STEM content knowledge. The results contribute to a better understanding of the role of mathematics/statistics in STEM education.