Physical models in the classroom "cannot be expected to represent the full-scale phenomenon with complete accuracy, not even in the limited set of characteristics being studied" (AAAS 1990). Therefore, by modifying a popular classroom activity called a "planet walk," teachers can explore upper elementary students' current understandings; create an environment where students generate questions based on their prior knowledge; and challenge students to think critically about the accuracy and limitations of a scale model of our solar system. (Contains 1 figure and 1 online resource.)