Upper Elementary School Children’s Adaptive Use of Subtraction by Addition: A Choice/No-Choice Replication Study Involving Two Choice Conditions

The current study examined upper elementary school children’s frequent, efficient and adaptive use of direct subtraction (DS) and subtraction by addition (SBA) when mentally solving multi-digit subtractions, replicating and expanding previous research by Torbeyns et al. (2018). First, children were offered subtractions in two choice conditions in which they had to indicate whether they would use DS or SBA to solve each item. In the choice-compute condition they were allowed to make actual calculations, in the choice-decide condition they were not allowed to do so. Thereafter, two no-choice conditions were offered (mandatory use of either DS or SBA). Results showed that children made frequent, efficient and adaptive use of the untrained SBA strategy. Furthermore, children were most adaptive for task and subject characteristics in the choice-compute condition. The current study confirms previous findings on SBA, and questions current classroom practices that focus heavily on the development of DS.