Educative curriculum materials--materials designed to promote both teacher and student learning--may help novice teachers learn how to engage in productive curricular planning. However, little is known about how educative supports within these materials should be written to best support teachers. This quasi-experimental study examines the affordances and constraints of two different forms of educative support, general supports and lesson-specific supports, in helping preservice elementary teachers critique and adapt science curriculum materials. The lesson-specific narrative supports helped the preservice teachers identify specific adaptations that they could make to lesson plans. They also led the preservice teachers to view the educative supports as useful and relevant, motivating them to use the supports in their analysis. In contrast, the general expository supports helped the preservice teachers identify principles of practice to use in their analysis of lesson plans. Implications for teacher education and curriculum materials design are discussed, including the need to provide a blend of both forms of support to help teachers make productive design decisions when planning with curriculum materials.