The International Mathematical Modelling Challenge (IM2C) adds a new incentive for applications of mathematics to problems beyond the classroom. Here we describe the design of a single package of support material for multiple audiences: on the one hand, for teachers intending to introduce modelling into curricula independent of Challenge involvement, on the other hand, for those wishing to enter teams in the Challenge. Some of the latter may also need modelling support provided for the former. It is necessary to identify and apply principles, some common to both and others directed to serving differing priorities within the two audiences. This involves addressing issues that continue to engage the international community, such as the purpose of modelling cycles, competencies, and the mentoring of student modellers. The chapter engages and illustrates such considerations.