With the rise of social network sites (SNSs), there is an increasing need for safety education within the current cyber society. To this end, a variety of educational materials have been developed to prepare children to be vigilant when interacting on such sites. However, little is known about the critical design aspects necessary to make these materials effective. In this study, we build on the results of two previous studies, in which we found that general instructional principles drawn from constructivism, such as collaborative learning, are not always appropriate to teach children how to behave safely online. This study therefore focuses on the importance of authentic learning and active learning as critical design features. A quasi-experimental study was conducted in secondary schools in order to compare the impact of two classroom interventions about the risks on SNSs. As part of the intervention, students were presented scaffolds towards different risks related to an SNS-profile through a series of questions. In the control condition, these questions concerned a simulated SNS-profile on paper containing signs of many risks. In the experimental condition, students had to answer the same questions about their own SNS-profile on a computer. It was hypothesized that the simulated profile would not be experienced as realistic, and that students would have difficulties identifying with it. On the other hand, teenagers were expected to be able to recognize more risks on the simulated ‘worst-case scenario’ profile than on their own profile, which would facilitate the scaffolding process in the control condition. The results of the study mostly confirmed these hypotheses. Furthermore, the question arose as to whether the intervention based on the student’s own realistic profile was educationally more valuable than the intervention based on the simulated profile, but no such added value was found. On the contrary, the scaffolding questions about the simulated profile were found to be more effective in teaching the teenagers about the different categories of risks that were tackled. Based on these findings, the importance of an authentic setting was put into perspective. Within the context of a classroom intervention to promote safety on SNSs, the exercise based on the simulated SNS-profile is put forward as the more effective teaching strategy.