and share both resources and results to lessen the individual costs for a thorough review.

It is realistic to expect that the guide can be used successfully in a variety of circumstances. The review process described in the guide contains recommendations that have been constructed to highlight only the principles and main tasks of each step. Specifics are left to the professional judgment of the facilitator and reviewers, because nearly every situation will have unique features. Suggestions for some specific situations have been included in "Constraints and Cautions" sections in Chapter 4.

The development process described in detail above provided Committee members with experiences and evidence concerning the need for a new kind of review instrument and the impact of myriad local concerns. A summary of the lessons learned may be useful in developing the capacity of the science education community to recognize and use effective instructional materials.

Training is essential if the evaluations are to be valid and useful. Field tests were carried out both with and without prior training. The sophistication and depth of the evaluations carried out after training were significantly improved compared to those obtained when training was omitted. In part this is because the tool asks the evaluators to exercise independent judgment without the guidance of detailed questions and check-off boxes for responses. This approach was not familiar to most evaluators, and they therefore benefited from training, including a group 'mock' evaluation, before they began their work. The requirement to exercise independent judgment and provide a narrative explaining the evidence for the judgment was challenging to participants in the field trials. Frequently, there was a request for more specific questions and accompanying boxes for checking off responses. The Committee responded positively to a few of these requests in subsequent versions of the tool, however the Committee concluded that the challenge to evaluators in the final tool is a useful one for fostering understanding of standards and for developing the capacity to carry out thoughtful evaluations.

As already noted, many teachers are unfamiliar with pertinent modern learning research. Training sessions need to include explication of the most significant aspects of this research. This can be accomplished by reference to the Standards and Benchmarks, supplemented by more recent work, such as How People Learn (NRC, 1999b).