Empirical studies on this issue involving word and intra-mathematical problems without
vague conditions have focussed on the investigation of instructional designs for prompting
multiple solutions. These designs involved presenting and comparing solution methods vs.
sequentially presenting different solution methods. In some studies, researchers did not find
any differences between approaches for students with different levels of prior knowledge, but
in other studies, students with better prior knowledge in the respective domain benefitted more
than other students from presenting and comparing multiple-solution methods (Große, 2014;
Reed et al., 2012; Rittle-Johnson et al., 2009, 2012). The rationale behind the finding that
novice students benefit from the sequential presentation of two solutions is that presenting and
comparing two new solution methods on an unfamiliar task can be too much for them. The results from the case study on solving modelling problems with vague conditions indicate that students do not have any difficulties finding a second solution if they have already found a first
solution (Schukajlow & Krug, 2013a). Indeed, the first and the second solutions for this kind
of problem may differ only in the assumptions about missing information, but they can involve
the same mathematical model, the application of identical mathematical procedures, and the
same interpretation. Thus, it is possible that only low or even zero effects of prompting
students to construct multiple solutions on the number of solutions developed or on students’
performance at posttest could be found for the specific kind of modelling problems that we
investigated in the current study