In order to teach a conceptual understanding of problems and their solution procedures as
well as to facilitate schema induction, worked-out examples have been proven more
effective than simply presenting abstract principles or having learners solve problems on
their own (Atkinson et al. 2000). Worked-out examples consist of a problem statement
(e.g., a word problem) and a step-by-step solution procedure, where the application of the
latter to the former is illustrated and explained. In order to help learners extract the relevant
structural features of problems, it has been proven useful to not only provide single
examples, but example combinations. Effective example combinations are characterized
by the fact that examples from the same problem category are embedded into different
cover stories and/or examples from different problem categories are embedded in the same
cover stories (Quilici and Mayer 1996; Scheiter and Gerjets 2005). Moreover, examples of
different problem categories should be presented in succession, thereby creating example
sequences of high variability (Paas and Van Merrienboer 1994; Van Merrie¨nboer et al.
2002) or high contextual interference (Magill and Hall 1991). Composing example combinations
and example sequences according to these guidelines, supports helpful inferences
with regard to the identification of structural commonalities and differences among
problems and thus enhances schema induction. With respect to supporting a meaningful
mental representation of solution procedures, highlighting the subgoal structure underlying
a solution procedure (e.g., by labels, Catrambone 1998), breaking down solution procedures
into smaller meaningful groups of solution steps that can be understood in isolation
(i.e., modular examples, Gerjets et al. 2004) as well as providing a rationale for the solution
procedure (process-oriented examples, Van Gog et al. 2004) have been shown to be
particularly effective instructional methods.