Inviting guest into our school is a classic teaching strategy. Welcoming other voices into the campus provides students with access to other perspectives, adds variety to the classroom routine, and demonstrates that learning is a collaborative enterprise. At the same time, however, presentations by guest experts are often plagued by a variety of design flaws that hinder their educational effectiveness. Guest experts, being unfamiliar with the mastery level of the students in the class, may speak over the heads of the students, or they may present their material at a level that is inappropriately introductory. Because they are generally unfamiliar with the class curriculum, they may repeat information that the students have already learned, or their comments may not connect in any clear way with what the students already know and what they are currently learning.