摘要：Determining whether a professional development program can be enacted with integrity in different settings and by different facilitators is critical to understanding efficacy. In this paper, we describe the two-stage preparation process of a facilitator as she prepared to use and adapt the highly specified Learning and Teaching Geometry video-based professional development materials with fidelity. The latter stage of the preparation process involved a rehearsal, during which the research team used two instruments to measure fidelity. Two existing instruments were used to explore fidelity through different lenses, including timing and modification of activities and learning goals. Results from both fidelity instruments indicate that the facilitator used the materials as intended by the developers. However, these instruments did not capture important information regarding modifications the facilitator made, including timing and content-focused adaptations. Suggestions are made with respect to measuring fidelity, preparing facilitators, and supporting productive adaptations.
关键词：Facilitator training;Mathematics education;Professional development
