To date, the failing effects of using peer assessment have been explained by deficits of the feedback, for example, the lack of clear suggestions on how to improve the work or students having different views of what counts as high-quality work. However, there is a need to further study the dialogicity of students as both providers and receivers of feedback in a social process of the science classroom. The study was conducted in four lower secondary school classes, school year 8 and 9, in two different schools. An intervention study was designed focussing on the topic of experimental design, involving the students in a process of peer assessment where they designed experiments individually, and then exchanged their designs, conducted each other’s experiments, provided feedback to each other and revised their original design after discussing the feedback in groups. Data were collected in the form of audio recordings of student discussions and written work. The peer feedback included varied aspects of the experiment regarding personal relevance, scientific inquiry or confirmation of what students already knew of health. Students could be supported in rejecting feedback, convinced to address feedback, or even renegotiate what counted as high quality in the discussion groups. The results show that the feedback the students provided to each other was used as frequently as the feedback they had received when they revised their design. Peer feedback that did not result in revisions could still be used for defining the quality of the experimental design. The potential for using peer assessment in science education could not only be evaluated through the students’ revisions.