Summary: The unifying theme of models was incorporated into a required Science Capstone course for pre-service elementary teachers based on national standards in science and mathematics. A model of a teeter-totter was selected for use as an example of a functional model for gathering data as well as a visual model of a mathematical equation for developing the mathematical relationship for a Class 1 lever, M1D1=M2D2. In this study, 20 student groups (n=72) collected data using the model in an inquiry-based activity. All groups developed the qualitative relationship, 13 groups developed a correct mathematical formula, 6 groups developed one-half of the relationship (X = mass x distance), and 1 group attempted to develop a procedural relationship. The pre-service elementary teachers used a variety of model types in the activity including visual/pictorial, functional/physical and mathematical-both graphs and formulas. The use of the teeter-totter model as a visual and functional model of a mathematical formula was a factor in developing the mathematical relationship. (ERIC)