In French-speaking Belgium, most programs were usually designed by practitioners (teachers) and supervised by an inspector, at least in official education. As part of a research funded by the Wallonia-Brussels Federation network, authors analyzed the science programs. On this basis, they highlight some of the difficulties to link to the design of programs. Authors put this observation in conjunction with the complexity to identify a coherent model that can support the design of programs. Moreover, they argue in favor of a steering of the writing process and offer some approaches to operationalize the theoretical and methodological contributions in the process of designing a curriculum.