Intertwining special education and mathematics education perspectives to design an intervention to improve student understanding of symbolic numerical magnitude

In our study we examined changes in student justifications over time with an intervention that drew from the best instructional practices in the fields of special education and mathematics education. These justifications were provided by teacher-identified struggling second-grade students while engaging in symbolic numerical magnitude comparisons. Following screening, we conducted 8 instructional sessions to promote conceptual understanding of fundamental ideas for numerical magnitude. Using data collected from 71 instructional tasks, we analyzed the types of justifications students provided and how these justifications changed over time. Prior to the intervention, most student justifications involved few components of a valid mathematical justification. Over the course of the study, students provided more valid and generalizable mathematical justifications.