“…Schwartz et al, (1989) and Kurland et aI., (1986) found that after months and sometimes even years of programming instruction, many students still display misconceptions in their conceptual knowledge and exhibit poor programming skills. Recent experimental studies (Bayman & Mayer, 1988;Bielaczyc & Brown, 1994;Schwartz et al, 1989) addressed successfully the conceptual and strategic deficiencies in students' knowledge. Students' development of effective programming skills was enhanced by enriching standard teaching materials with supplements that emphasised the underlying semantics of programming (Bayman & Mayer, 1988), by providing complete descriptions of the problem-solving steps used by the experts by fostering the development of an appropriate mental model of the operations of the computer (Schwartz et a!., 1989) or by fostering students' collaborative explanations (Bielaczyc, Brown, & Pirolli, 1994).…”