According to Brookhart (2013), rubrics can be defined as a “coherent set of criteria for students' work that includes descriptions of levels of performance quality on the criteria”. What does it mean in practical terms? Unlike abstract concepts such as As and Bs, or grades that vary from one to ten, rubrics describe, with some level of detail, the different levels of performance and what they are worth in terms of grades.

They are particularly important in PBL for two main reasons: first, they are much more relevant for formative assessment, as they show students exactly what they have done right, as well as where they need to improve. Secondly, using rubrics enables students to contribute to building the criteria and descriptions together with the teacher, which gives them a sense of belonging while promoting engagement and autonomy.