Comparative judgement is a relatively new way of facilitating peer-assessment where students are shown pairs of other students' work and judge which of the two is better. Literature on example-based learning suggests that students should be able to learn from comparative judgement. We present the case of one student, Josie, whose understanding of rational inequalities did not improve while assessing other students work comparatively. We argue that her self-explanation attempts were limited because comparative judgement created an environment that threatened her goal of understanding. Knowing the correct answer may have helped alleviate some of these issues.