https://www.fcd-us.org/prekindergartners-left-behind-expulsion-rates-in-state-prekindergarten-programs/
Pre-K students are expelled at a rate more than three times that of children in grades K-12, according to a primary study by Yale Child Study Center researcher Walter S. Gilliam. The lowest rates of expulsion were reported by teachers who had an ongoing, regular relationship with a behavioral consultant. In classrooms where the teacher had no access to a behavioral consultant, students were expelled about twice as frequently. The study reports on expulsion rates by program setting gender, race/ethnicity and state.