Despite a decline in popularity within US society, posters continue to hold a prominent place within middle and high school science classrooms. Teachers' demand is satisfied by governmental and non-profit science organizations that produce and disseminate posters as tangible products resulting from their research, and instruments to communicate scientific content to teachers and students. In this paper, we examine the design of such posters for their implied, underlying assumptions about learning and their alignment to the unique setting of the classroom. Based on this analysis and research into both cognition and the design of multimedia, we propose a design framework for educational posters that activates students' attention, catalyzes cognitive processing, provides a framework to guide student's construction of knowledge and connects to extended learning through live or web-based exploration of phenomenon. Based on this framework, we present a prototype poster and explore implications for poster producers, teachers, and academic researchers. (Contains 2 tables and 3 figures.)