David Patrick is Senior Math and Science Curriculum Developer at Art of Problem Solving (AoPS) and Director of the San Diego Math Teachers’ Circle. He is the author or co-author of 4 of AoPS’s textbooks and an instructor for the AoPS online school. As a high-school student, Dave was a USA Mathematical Olympiad winner in 1988. He was an acting Assistant Professor at the University of Washington before joining AoPS in 2004. Dave has been an invited guest instructor at multiple teachers’ circles in the San Francisco Bay Area and at the Navajo Nation Math Circle, and has led professional development sessions for teachers in San Diego, Charlotte, Des Moines, Minneapolis, and perhaps other places that he can’t remember right now.