This study is a randomized control trial of full- versus half-day prekindergarten (pre-K) in a school district near Denver, Colorado. Four-year-old children were randomly assigned an offer of half-day (4 days/week) or full-day (5 days/week) pre-K that increased class time by 600 hours. The full-day pre-K offer produced substantial, positive effects on children’s receptive vocabulary skills (0.275 standard deviations) by the end of pre-K. Among children enrolled in district schools, full-day participants also outperformed their peers on teacher-reported measures of cognition, literacy, math, physical, and socioemotional development. At kindergarten entry, children offered full day still outperformed peers on a widely used measure of basic literacy. The study provides the first rigorous evidence on the impact of full-day preschool on children’s school readiness skills.

中文翻译：

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全日制幼儿园的影响：影响儿童入学准备的实验证据

这项研究是在科罗拉多州丹佛市附近一个学区进行的全日制和半日制幼儿园前（K幼儿园）的随机对照试验。四岁的孩子被随机分配给幼儿园前半天（每周4天）或全天（每周5天）的要约，这使上课时间增加了600小时。幼儿园前全日制课程对孩子的接受词汇能力产生了积极的影响（标准偏差为0.275标准偏差）。在就读于地区学校的儿童中，全日制参与者在教师报告的认知，识字，数学，身体和社会情感发展方面的表现也优于同龄人。在幼儿园入学时，全日制儿童在广泛使用的基本识字率方面仍优于同龄人。