Teaching mental arithmetic in the Lutheran institutions of Serra do Tapes, Rio Grande do Sul, Brazil

This paper intends to understand strategies of problem-solving by means of mathematical mental calculation and to observe the importance of these strategies in the learning disseminated in Lutheran community schools in Serra dos Tapes (Rio Grande do Sul, Brazil). These schools have been created based on a religious community design during German immigration in the state of Rio Grande do Sul, Brazil. To achieve the purpose of this study, we looked at oral narratives from individuals educated between 1930 and 1970, as well as speeches published by the children's magazine "O Pequeno Luterano" (The Little Lutheran), focused on mathematical knowledge and mental arithmetic. It was observed, hence, how mathematical learning was related to the reality of Lutheran students from rural areas. For that, we investigated mathematical contents published by the magazine as curiosities and guessing games, which stimulated mental arithmetic in children through quizzes and playful activities. Moreover, the narratives help understand the use of mental mathematical skills in the school routine, as well as revealed the decrease of such knowledge in the next generations.