In this article we examine the activities of 2 public lessons prepared and conducted by a group of elementary school teachers in China. We employ the conceptual lens of deliberate practice to understand how the public lesson activities possibly contributed to improvement of the teachers' knowledge and instructional performance. We found that teaching mathematics as deliberate practice through public lessons gave the teachers an opportunity to refine their instruction in 3 core aspects that included designing appropriate mathematical tasks for students, teaching the difficult mathematical idea, and using mathematically, pedagogically appropriate language.