A Virtual Number Line Intervention Package to Support Addition and Subtraction for Students With Intellectual Disability.

This article focuses on a study examining the effectiveness of an intervention package—comprising modeling, a virtual number line app, and a system of least prompts (SLP)—to support high school students with intellectual and developmental disabilities (IDD) in acquiring, maintaining, and generalizing double-digit addition and subtraction skills through online instruction. Conducted with three high school students with IDD in a rural special education setting, the study found a functional relation between the intervention and improved accuracy and independence in solving math problems, though students struggled to maintain skills without prompts and were unable to generalize these skills to real-life contexts involving money and time. The findings support virtual manipulatives as a promising tool for teaching mathematics to secondary students with IDD online, while highlighting the need for explicit instruction targeting generalization and independence. Limitations include the small sample size, lack of explicit generalization training, and challenges inherent in remote data collection.