The AP Calculus Course and Exam Description includes the Mathematical Practices for AP Calculus. One of these practices is reasoning with definitions and theorems, calling for students to build arguments, justify conclusions and confirm results, verify assumptions before applying a theorem and produce examples and counter examples. The session will explore what this looks like in calculus and consider what should students encounter in second year algebra and precalculus in order to be prepared for implementing this practice in calculus. Presented by Gail Burrill.