This study focuses on the aspects in the cognitive structure that should be trained to develop Dutch students modelling without actual modelling lessons. The research used 16 fifth-grade beta coursed students to study the development of the cognitive structure and its relation to modelling. The methodology is based on the Conceptual Content Cognitive Map Method of Kearney and Kaplan (1997), while Tall's (2013) theory is the theoretical framework. Data are collected by a cognitive test and a modelling test. The results show that students with a rich cognitive structure develop compression. Thus, teachers should focus on the connections between mathematical concepts as a solution for this problem.