This article explores the results of a rubric-based formative assessment of an eportfolio task as part of a pedagogical subject on a weekly basis during the first year in the Teacher Education programme of the University of the Balearic Islands. The study aims to explore the possibilities of the rubric usage for formative assessment and in particular, is aimed at exploring the consistency of students' improvement throughout the semester. The literature review briefly covers research on closely related concepts such as formative assessment and feedback along with process eportfolios for reflective tasks, which are all aimed at achieving higher-level cognitive skills and, eventually, self-regulated learning. Data, which is obtained from students' performance and statistically analysed, reveals evidence of the general improvement of results throughout the semester with the majority of students moving from lower to higher levels. Furthermore, data obtained also allows observing some difficulties for reflective skills. Conclusions reflect on challenging implications for sustainable transferrable practices, self-regulated learning and formative assessment.