Redd, Zakia; Boccanfuso, Christopher; Walker, Karen; Princiotta, Daniel; Knewstub, Dylan; and Moore, Kristin. Expanding Time for Learning Both Inside and Outside the Classroom: A Review of the Evidence Base. Santa Monica, CA: RAND Corporation, August 2012. Also available in print form.
This report reviews some 80 studies of initiatives to lengthen the school day or year or offer learning opportunities outside of school hours. Most of the studies lack the rigor needed for firm evidence of the impact of expanded time efforts on children, the report emphasizes. But the slim evidence available suggests that extending school time can help raise academic achievement, while out-of-school opportunities can boost "precursors" to achievement, such as educational expectations. And in all cases, program quality and implementation "matter a great deal."