Scale measurement and ratio and proportion are topics that fall clearly in the middle-grades mathematics curriculum in Texas. So does the solar system. In their experience, the authors have found that students have trouble manipulating, much less comprehending, very large numbers and very small numbers. These concepts can be brought into students' realm of understanding through scale--scaling down very large objects and scaling up very small objects to develop models that can be seen and manipulated. Realizing that their middle school science colleagues were teaching the solar system while they were teaching scale, the authors hit upon the idea of enhancing their content with their mathematics. After all, who hasn't seen a bad model of the solar system, with disproportionate planet sizes and distances? Let the math teachers help! Their goal was to develop a three-to-five-day unit that would refresh students' measurement skills, link those skills to the concepts of scale and proportion, and introduce the real-world applications of these concepts by using modeling and simulation to interest their students in their continued study of ratio; and proportion. The authors designed activities that build upon each other and link what students already know about measurement to how they can use measurement as a tool for creating scale models. The unit includes an introductory activity on measurement, two exploration activities, and a final demonstration of students' understanding of scale models. It introduces students to a teacher-made simulator developed in a spreadsheet that they can use to explore scale without getting overwhelmed with manipulating the vast distances in the solar system. (Contains 5 figures and 6 online resources.)