When asked to examine particular features of a paper, students often feel most comfortable moving through a sequence from simply identifying a feature to evaluating it to suggesting revisions. Especially if you give students multiple peer-review opportunities, consider using progressive workshop sheets, building on tasks required in previous workshop sheets. Label the level of each task clearly so that students know if they are to identify features or suggest revisions.
The following items appear in sequence on a peer-review worksheet distributed to a freshman composition class. Notice how the instructions move students from identifying a thesis to evaluating it to suggesting revisions:
Mark and label the writer's thesis in the draft. In the space below, "unpack" the thesis.
Is the thesis clearly debatable? Suggest one way the thesis might be narrowed or focused, if necessary.