On students’ difficulties in changing their original procedure on the example of a task concerning differential comparison

Recognising and understanding the difficulties, which students show at different levels of teaching mathematics, can result in increased effectiveness of teaching. In this article, difficulties of students from the second to the fifth grade of primary school are analysed, revealed while they were solving tasks regarding differential comparison. Those difficulties, seemingly related to a relatively easy subject, make one realise how complex the process of learning mathematics is. The problem of differential comparison is only an example aimed at illustrating what impact previous experiences of a student have on the formation of pieces of their new knowledge