Mathematization is a critical competency in the modelling process. This study aims to elicit prospective mathematics teachers' mathematizing through the analysis of their solution approaches to a modelling problem related to the bales of straw. This study was conducted with 75 fourth-year prospective mathematics teachers (PMTs) enrolled in a teacher training program in Elementary Mathematics Education (EME) that refers to education for children aged 10-13 years. The main data sources were the PMTs' written and verbal explanations and drawings. The study results revealed that PMTs used four solution approaches: trigonometric, estimation of measurements, area/perimeter, and similarity of triangles in the modeling task. They mostly solved the problem using trigonometric ratios and measurement estimation approaches. The solution approaches included different levels of mathematization. However, the mathematical modeling task required PMTs to develop an estimated numerical result, about sixty percent of the solutions had numerical results. However, more than half of the numerical results were implausible. We suggest that looking at the successful and unsuccessful solution attempts made by PMTs during the modeling process can be a good way to learn more about the modeling process and mathematization competencies.