Absence of conflict of interest

The Agodini et al. (2009) study summarized in this intervention report was prepared by staff of Mathematica Policy Research. Because the principal investigator for the WWC review of elementary school mathematics also is a Mathematica staff member, the study was rated by staff members from the University of Wisconsin and the Optimal Solutions Group. The intervention report was reviewed by the deputy principal investigator, a WWC Quality Assurance reviewer, and an external peer reviewer.