An EdPolicy Works working paper reports on a randomised controlled trial of the effects of full- versus half-day preschool on children’s school readiness.
Four-year-old children in a US school district near Denver were randomly assigned to either half-day (n=112) or full-day (n=114) preschool classrooms. To examine the impact on children’s outcomes, Allison Atteberry and colleagues assessed children’s receptive vocabulary skills using a standardised test in which children point to one of four pictures that best corresponds to a spoken word. The researchers also administered a developmental screening tool to assess children’s developmental abilities in relation to school readiness. Both assessments were conducted within the first month of the first term, and again in the last month of the last term.
Their results showed that full-day preschool had positive effects on children’s vocabulary skills (+0.27 standard deviations) by the end of the school year. Positive impacts were also indicated on cognition, literacy, maths and physical skills – with effect sizes from +0.19 to +0.39.
Source: The effects of full-day pre-kindergarten: experimental evidence of impacts on children’s school readiness (July 20189), EdPolicyWorks Working Paper Series No. 64.