The paper describes the first results of a research study focusing on the process of generalization in primary school pupils. The research was conducted in two stages - individual solving of problems by pupils, analysis of pupils' solutions and selection of pupils for the second stage of the research which had the form an individual task-based interviews.
The research tool was a set of different kinds of tasks of graded difficulty that allowed easy modification for individual pupils. By analysing the solution of two series of tasks by 3rd graders of primary school we can state that with appropriate formulation of tasks some pupils are able to formulate ideas at a general level and use the language of letters.