Despite extensive research suggesting the importance of students developing strong foundational math skills during early grades, more than 60% of 4th graders in the United States lack proficiency in mathematics. Such data are influenced by several factors, including summer learning loss in math, negative impacts from the COVID-19 pandemic, and a need for more research on intervention programs for elementary-aged students experiencing difficulties in math. The goal of the present study was to use a multiple-baseline experimental design to evaluate the Accelerating Mathematics Performance with Practice Strategies (AMPPS) program when implemented one-on-one, virtually, and during the summer with second- and third-grade students experiencing math difficulties. Overall, results showed that all students: (a) improved their addition and subtraction fluency during the AMPPS intervention phase, but three of the four participants showed relatively stronger gains; and (b) found AMPPS to be an acceptable intervention when used virtually during the summer. Findings are discussed within the context of summer learning, COVID-19, and potential opportunities to benefit from interventionists' virtual implementation of evidence-based math programs.