When you start to see third grade retention policies as less of an intervention and more about how they change adult behavior, you can see it show up in the research literature. For example, a study from Michigan — a state where, thanks to various exemptions and remediation efforts, the number of kids who are actually retained is just 0.5% — found positive effects of its third grade reading law even in districts that did not hold any students back. A Florida study found that flagging a child for retention improved the academic outcomes of their younger siblings. One of the study’s authors speculated that, “the high-stakes retention signal for the older siblings might inform parents and educators about the educational needs of the younger sibling and induce them to act.”