<p>Group work assessment is described by teachers as challenging, especially assessing individual students’ knowledge developed in group work (i.e. individual group work assessment) since it entails a procedure of discerning each student’s knowledge from the group’s collective process. The aim of this study is to increase knowledge of how upper secondary teachers’ actions enable or hinder their collection of evidence for individual group work assessment of students. Particularly, the study investigates how individual oral cross-group presentations can be used to assess students’ individual knowledge developed in group work. Data consists of 23 video recordings from upper secondary teachers’ assessment of oral presentations in cross-groups followed by six interviews with the participating teachers. Data has been analysed using reflexive thematic analysis in which three themes were constructed: (a) Teachers’ frames that enable or hinder collection of evidence, (b) interactions that enable or hinder teachers’ collection of evidence, and (c) students’ behaviours that hinder collection of evidence. The results illustrate the importance of interaction by implementing the method of cross-group presentations by being active as a teacher, asking questions, and giving reflections. Interaction may enable reliable evidence that goes beyond students’ boundness to manuscripts. Potential hinders for teachers to collect evidence of students’ individual knowledge using cross-group presentations are aspects such as having enough time for presentations and interactions to enable sufficient evidence or students’ nervousness and silence that may hinder students from demonstrating their knowledge.</p>