This paper is about the representation young students use when they are working on a problem-solving task on combinatorics. Results from previous studies on young students and combinatoricshave shown connections between the representations used and to what extent students solved the task. Based on these previous results, young students in this study were interviewed about their choice ofrepresentation. In this paper, the rationales expressed by the students are connected to therepresentation and stage of systematization shown in their documentation. The results indicate thatdifficulties in representing the context of the problem-solving task, may force some of the students towork with a representation on a level of abstraction not suitable for them. Working with representations on a non-suitable level of abstraction may in turn influence how the students manageto solve the problem-solving task.