In this paper, we describe our learning progressions approach to early algebra research that involves the coordination of a curricular framework, an instructional sequence, written assessments, and levels of sophistication describing the development of students' thinking. We focus in particular on what we have learning through this approach about…

Consistent with a Diathesis × Stress model, it was hypothesized that anxious solitude (individual vulnerability) and the middle school transition (environmental stress) would jointly predict peer exclusion and victimization trajectories. Youth (N = 688) were followed from 3rd through 7th grade, with the middle school transition in 6th grade.…