ABSTRACT
In an effort to improve the didactics of informatics in general and of programming in particular, educators have developed many pedagogical soft-ware tools, especially visual tools. The first attempt in 1981 was by Ronald Baecker who produced a file called Sorting Out Sorting that animated the execution of various sorting algorithms (Baecker, 1998). A comprehensive, though now somewhat dated, review of research on software visualization can be found in Stasko et al. (1998). Software visualization covers a wide range of topics as can be seen in the taxonomy given by Price, Baecker, and Small (1998). Most effort has been invested in at the abstract level of algorithm visualization (Hundhausen, Douglas, & Stasko, 2002; Shaffer et al., 2010). A website devoted to the topic contains links to hundreds of software tools ( https://https://algoviz.org/" xmlns:xlink="https://www.w3.org/1999/xlink">https://algoviz.org/">; ). Our interest is at the more concrete level of program visualization.
