This study aimed to examine prospective teachers' anticipations of students' thinking on the measure of the arc and measure of the central angle, circumference, and area of the circle and to explore the changes in their anticipations as they conduct three lesson study. For this purpose, case study method was used. Three prospective middle school mathematics teachers participated in the study and completed three lesson study. The data were analyzed in terms of three components: the prospective teachers' anticipations of (1) how students' would think; (2) what difficulties they would have; and (3) what powerful ideas they would have. The results showed that lesson study cycles with real classroom experience provided opportunities for the prospective teachers to develop anticipations of students' thinking.