Both comparison and direct instruction have the independent potential to direct learners' attention to important aspects and thereby to highlight the inherent key features and difficulties of the concepts to be learned. Regarding the particular potential of direct instruction, the question arises of whether teacher guidance in contrast learning that explicitly emphasizes differences between juxtaposed concepts reduces cognitive load to a similar level as that experienced in sequential learning. Through this reduction, the desirable difficulty and interconnecting effects of contrasted comparison might be neutralized. For the current experiment, this could mean that if the teacher strenuously emphasizes that addition and multiplication algebra problems must be treated differently, it may not matter whether direct instruction is based on contrasted or sequential material. Put differently, contrasted comparison may merely compensate for the deficiencies of self-learning, thereby rendering itself superfluous under direct instruction.
Despite these objections, there are nonetheless good reasons to assume that contrasting will also unfold its particular potential under direct instruction. When addition and multiplication are directly instructed in sequential order, key features and difficulties of both principles can be highlighted. However, the sequential practice of addition and multiplication problems may prevent learners from developing deeper insights into the differences between the two operations.
We therefore consider it necessary to examine the effects of our successful contrasted introduction of two algebraic principles in a direct instruction format. When new instructional materials, techniques or tools are developed, they are often investigated using self-learning material or computer-based methods. Because findings may easily be too broadly generalized, it is important to examine promising methods in alternative formats.