Achieving high-quality preschool at scale is challenging; to do so likely entails a combination of program standards, teacher qualifications and compensation, on-site quality monitoring, and professional development (PD). This study aims to examine the impact of investments in PD within the context of an expansion of universal preschool in one of the nation’s largest school districts. We leverage the opportunity provided by a “natural experiment” to estimate PD’s effects that embeds an evidence-based math curriculum in interdisciplinary units of study with coaching support on teacher math practices. A total of 95 schools participated in this study (51 treatment and 44 comparison schools). Treatment sites implemented more teacher-led math activities for a longer period compared to control sites. The size and magnitude of the impacts of a curriculum and PD program implemented at scale were comparable to results from studies of small-scale efficacy trials.

大规模实现高质量的学前教育具有挑战性；为此，可能需要将课程标准，教师资格和薪酬，现场质量监控以及专业发展（PD）结合起来。这项研究旨在研究在全国最大的学区之一的全民学前教育扩展的背景下，对PD进行投资的影响。我们利用“自然实验”提供的机会来评估PD的效果，该效果将基于证据的数学课程嵌入跨学科的学习单元，并在教师数学实践方面提供指导支持。共有95所学校参加了这项研究（51所治疗学校和44所比较学校）。与控制站点相比，治疗站点在更长的时间内实施了更多由教师主导的数学活动。