Background: Lack of content knowledge (CK) is problematic in teaching in classroom subject areas and in physical education. There is a dearth of data-based research on interventions aimed at helping teachers acquire CK and, in turn, on the effects of CK on student learning. Aim: To investigate the effect of professional development, in the form of a CK workshop, on the quality of instruction and student learning. Participants: Two beginning middle-school physical education teachers of both genders who had no experience in playing or teaching badminton were purposefully selected. A total of 48 students (2 teachers × 4 classes × 6 students) participated in this study. Data collection and analysis: Descriptive statistics for students' and teachers' data were reported. General linear models with a nested design structure were used to examine the statistical differences of the mean percentage of students' correct or incorrect performances between the comparison and experimental classes. Findings: Most students rarely performed the skills correctly in the comparison classes, whereas the students tended to perform the skills correctly in the experimental classes. Both teachers used more correct task representations and more mature tasks by using more diverse forms of visual and verbal representations in teaching after the badminton CK workshop. Conclusion: The results of this study indicate that a relatively short, 4-hour CK workshop was effective in changing teacher pedagogical content knowledge (PCK) behaviors. More importantly, the results also demonstrate that these changes in teacher PCK behaviors produced better student learning. However, levels of procedural fidelity of workshop in teaching need to be further investigated.