Advantages and disadvantages of using loops in algorithms: conceptions of pre-service primary teachers learning Scratch

International audience ; The purpose of this paper is to explore pre-service primary teachers' conceptions of loops for drawing squares in their early stages of learning Scratch. Twenty-six pairs of student teachers, all with some experience in teaching mathematics at primary school level, explain the advantages and disadvantages of using loops in Scratch. Qualitative content analysis of their written explanations revealed three categories: (1) the higher efficiency of loops is seen as a clear advantage, (2) their narrower range of applicability as a clear disadvantage, and with regard to (3) the cognitive demand of loops, the responses are contradictory. In addition to some misconceptions, we could identify a key fact that student teachers must know in order to competently handle loops in Scratch, that is different outputs may occur from the same instruction if the instruction is inside a loop.