This study is the first phase of an on-going study. It shows the first implementation of a teaching-learning sequence designed to facilitate the understanding of the notion of a living being in initial teacher training using modelling approaches. It aims to analyse the knowledge progression of the participants (N=51) through a retrospective analysis, employing an open-ended questionnaire and a rubric. To achieve this, a comparative pre-test-post-test design was used, utilising an open-ended questionnaire. The results show progression in the management of the living being model after comparing knowledge before and after implementation. The results suggest the usefulness and interest of the modelling approaches in teaching this topic, while also highlighting the need for modifications to the didactic sequence employed.