- On average, African American and Hispanic students were in 1st and 3rd grade classrooms where one in four students were reading below grade level.
- Estimated negative effect on African Americans on reading achievement gains of being lower grouped for reading instruction in 3rd grade is about .23 of a standard deviation of nongrouped students.
- The positive effect on African Americans of being higher grouped is .12 of a standard deviation above nongrouped African American students. The same is true for Hispanics but only in 1st grade.
- Estimated negative effect on Hispanics on reading achievement gains of being lower grouped for reading instruction in 3rd grade is about .15 of a standard deviation of nongrouped students.
- The positive effect on Hispanics of being higher grouped is .21 of a standard deviation above nongrouped Hispanic students.
- Students who are lower grouped for reading instruction learn substantially less and higher-grouped students learn slightly more by the first and third grades, compared to classroom that do not practice grouping.
- Calls into question the notion that ability grouping is a beneficial practice in early elementary school years.
- Study supports the differential effects hypothesis of ability grouping.
- Suggests that ability grouping has substantial implications for early learning trajectories of African American and Hispanic students.