Science students should use mathematical and computational thinking to explain phenomena, but few examples of teachers engaging students in this important scientific practice have been found. This article describes a strategy for enhancing a lesson in which students use a mechanistic model to explain friction by adding mathematical and computational thinking. This helps students express their ideas more precisely with models that have predictive power. The approaches described in this article could be a framework to engage students in mathematical and computational thinking in other topics in physics (e.g., studying collisions related to drop height and resultant bounce height for a ball) and in other disciplines (e.g., the study of population ecology in the life sciences). Adding mathematical and computational thinking is appropriate and important for all students as they go about making sense of the world in science class.