Simulations are traditionally divided into three phases, namely preparation, interaction, and debriefing. This article argues that the first phase has been neglected. The preparation phase is indeed widely seen as necessary but merely instrumental to the interaction phase of simulations rather than as a self-contained activity that may also provide an opportunity to make the most of their pedagogical potential. This article explains how writing a briefing memo to prepare a simulation challenges this taken-for-granted view. After outlining the reasons why I asked the students of my Introduction to International Relations module to write a briefing memo about the conflict in South Sudan in preparation for a simulation of the negotiation of a peace agreement, the article explains how it can be used to generate a stimulating class discussion. It then emphasizes how the three phases of the simulation fruitfully complement each other and allow teachers to go beyond the instrumentalist conception of the preparatory phase. Finally, the conclusion reflects about the "portability" (Kollars and Rosen 2016) of the briefing-negotiation-debriefing format outlined in this article.