ABSTRACT
The aim of this paper is to describe a teaching proposal that promotes algebraic thinking through the expression and justification of mathematical ideas when solving tasks related to three different approaches to algebraic thinking. We designed a classroom teaching experiment implemented during the COVID pandemic in Chile. We analyze the oral discussions and the written productions of children in fourth grade (9-10 years old). The results show that the children expressed and justified increasingly sophisticated algebraic ideas. That is, they gradually adopted a more precise and mathematical language. We conclude that this modality of work, in which the algebraic character of arithmetic is highlighted through various instances of discussion, is a contribution for teachers, by guiding them in addressing current teaching challenges. © 2023 Universitat Autonoma de Barcelona. All rights reserved.