Resumo

BARRERA-MORA, Fernando; REYES-RODRIGUEZ, Aarón  e  MENDOZA-HERNANDEZ, José Guadalupe. Mental calculation strategies for addition and subtraction developed by middle school students. Educ. mat. [online]. 2018, vol.30, n.3, pp.122-150.  Epub 07-Fev-2022. ISSN 2448-8089.  https://doi.org/10.24844/em3003.06.

Mental calculation strategies play an important role in the development of students’ number sense. In this regard, we sought to determine how students of a public middle school (distance education program), located in a rural community in the state of Hidalgo, Mexico, can develop mental calculation strategies when performing tasks involving addition and subtraction, in a shopping context. Eight different strategies were identified, some of which used fantasy money as a representation system that helped students to decompose quantities. They referred to strategies used by people, without schooling, when they receiving money back after paying for a purchase in the market. Strategies such as removing one to the minuend in a subtraction with regrouping also appeared, to obtain one addition without regrouping. That is, we identified a transfer of mental calculation strategies to paper and pencil scenarios, which facilitate calculations to solve a problem. This is an indicator of creativity and understanding of numbers and operations.

Palavras-chave : number sense; mental calculation; addition and subtraction; tasks in a shopping context.