A large body of research has shown that for novice learners, instruction that relies more heavily on worked examples than on problem solving, is more effective for learning as shown by higher test performance. Moreover, this beneficial effect is often obtained with less acquisition time and lower cognitive load during acquisition and test phase.…

Second and third graders from six Dutch elementary schools (N = 168) solved two sets of almost identical addition and subtraction sums at a two-week interval. Inconsistency in strategies, which characterized half the subjects, was related to unfamiliar sums and resulted in misinterpreted errors. (TJH)