The growth in online professional development opportunities for teachers, due to the COVID-19 pandemic, prompts us to question what the most effective practices of facilitating professional development online are and what design elements of online professional development (OPD) programs improve teachers' content and pedagogical content knowledge (PCK). These questions are critical to the successful design and delivery of OPD for teachers. To date, there is no systematic review that provides answers to these questions. Hence, this review presents a synthesis of 11 studies that systematically examine experimental and observational studies that tested or evaluated formal OPD programs for teachers. Eight studies were quantitative and three were mixed methods detailing evidence of teachers' OPD program effectiveness, including design elements, that lead to teachers' improved: content knowledge; PCK; beliefs about teaching; self-efficacy; and instructional practices. Design elements identified included a focus on learner supports, further acquisition or development of PCK, engagement, flexibility, individual difference in learners and learning styles, practical learning activities, reflection, relevance and application of knowledge and skills. The analysis uncovers a primary issue that few available publications of teachers' OPD are strong methodologically. This systematic review's findings report on design elements that lead to effective OPD learning experiences for teachers.

由于COVID-19大流行，教师在线专业发展机会的增长促使我们质疑促进在线专业发展的最有效实践是什么，以及在线专业发展（OPD）计划的哪些设计要素可以提高教师的学习水平和教学内容知识（PCK）。这些问题对于教师成功设计和交付OPD至关重要。迄今为止，还没有系统的评论可以提供这些问题的答案。因此，本综述提供了11项研究的综述，这些研究系统地检验了实验和观察性研究，这些试验或观察性研究为教师测试或评估了正式的OPD计划。有8项研究是定量的，有3项是混合方法，详细说明了教师OPD计划有效性的证据，包括设计要素，导致教师的进步：内容知识；PCK; 关于教学的信念；自我效能感 和教学实践。确定的设计要素包括：对学习者的支持，对PCK的进一步获取或发展，参与度，灵活性，学习者和学习风格的个体差异，实际学习活动，反思，相关性和知识和技能的应用。分析发现了一个主要问题，即在方法上，很少有可用的教师OPD出版物。该系统评价的结论报告涉及可为教师带来有效OPD学习经验的设计元素。PCK的进一步获取或发展，参与度，灵活性，学习者和学习风格的个体差异，实际学习活动，知识和技能的反思，相关性和应用。分析发现了一个主要问题，即在方法上，很少有可用的教师OPD出版物。该系统评价的结论报告涉及可为教师带来有效OPD学习经验的设计元素。PCK的进一步获取或发展，参与度，灵活性，学习者和学习风格的个体差异，实际学习活动，知识和技能的反思，相关性和应用。分析发现了一个主要问题，即在方法上，很少有可用的教师OPD出版物。该系统评价的结论报告涉及可为教师带来有效OPD学习经验的设计元素。