Although mathematical modelling in the first years of school is mandated in some curricula and could provide opportunities for children to engage with various mathematical concepts across different contexts, very little research has investigated this. In this paper, we analyse number stories created by second-grade, seven-year-old children, that involve two or more arithmetic operations, otherwise known as two-step problems, by exploring their relationship to mathematical modelling. Although two-step textbook problems are usually considered too complex for young children, mathematising aspects of their everyday lives in number stories while being in control of the modes of expression seems to facilitate some children to engage with more complex problems. Reconstructing number stories as mathematical modelling provides insights into how number stories as a teaching tool could contribute to discussions about how to facilitate children to move from informal strategies for solving specific problems to general strategies that can be used for a range of problems.