Background: Social comparisons between pupils are especially relevant at school. Such comparisons influence self-perception and performance. When pupils evaluate themselves more negatively and perform worse after an upward comparison (with a better off pupil) than a downward comparison (with a worse-off pupil), this is a contrast effect. On the other hand, when they evaluate themselves more positively and are better after an upward than downward comparison, this is an assimilation effect. Aims: We examine assimilation and contrast effects of comparison in the classroom on pupils' self-evaluation and performance. Previous work by Fayant, Muller, Nurra, Alexopoulos, and Palluel-Germain (2011) lead us to hypothesize that approach vs. avoidance moderates the impact of upward vs. downward comparison: approach should lead to an assimilation effect on self-evaluation and performance, while avoidance should lead to contrast on self-evaluation and performance. Methods: To test this hypothesis, we primed pupils with either approach or avoidance before reading upward or downward comparison information about another pupil. We then measured self-evaluation (Experiment 1) and performance (Experiments 1 and 2). Results: Results confirmed our predictions and revealed the predicted interaction on self-evaluation (Experiment 1) and performance (Experiment 2): approach leads to an assimilation effect (in both experiments) whereas avoidance leads to a contrast effect (in Experiment 2). Conclusions: These experiments replicate previous studies on self-evaluation and also extend previous work on performance and in a classroom setting. Priming approach before upward comparison seems especially beneficial to pupils.