Many talented students in under-resourced schools do not reach their full potential. Research shows that by sixth grade, children born into poverty have likely spent 6,000 fewer hours learning than their middle-class counterparts. Higher Achievement, an intensive summer and after-school program, aims to close that learning gap. It offers…

This addendum to previously published results presents alternative analyses of data from large-scale effectiveness studies of Cognitive Tutor Algebra I in middle schools and high schools. These alternative analyses produce results that are substantively the same as previously reported. We find a significant positive effect of 0.21 standard…