The introduction of new technologies in classrooms is often thought to offer great potential for advancing learning. In this article, we investigate the relationship between such expectations and the post-implementation evaluation of a new technology in an educational setting. Building on psychological research, we argue that (1) high expectations ("ex ante") can undermine the approval ratings of new technologies ("ex post"); and (2) individuals' post-implementation evaluations are more likely to exceed their expectations when they can exert power over the introduction of a new technology. We test these predictions on a sample of 750 respondents from primary and secondary schools in Flanders with and without tablet computers. Our findings are supportive of both theoretical predictions.