Code tracing (or program sketching) is a useful technique for both students and professionals to understand syntactic and semantic details of code. Emphasizing and exploring this skill leads students to a deep understanding of their code in the short term and ultimately, their evolution into competent programmers in the future. In this paper, we provide evidence that a careful incorporation of the concept of scoping into code tracing techniques is fundamental to achieving this successful student transition. To this end, we present a formalized pencil-and-paper code tracing strategy for CS1 called Visualized Scope Tracing (VST), with scoping as a key underlying theme that elegantly addresses code blocks, function stacks, recursive structures, pass-by-reference, arrays, pointers, and parallel code.

Furthermore, we study the impact of our code tracing approach on CS1 students at a small liberal arts institution over a 10-year period. The goals of this work are twofold: describe how to easily (and naturally) integrate VST into any CS1 curricula; second, show demonstrable improvements on student understanding using our technique. Our findings suggest that VST is not only effective at improving students’ skills in CS1, but that it has a positive, long-lasting impact on their academic performance in CS2.