The Project Brief - On not hard-wiring a PBL too soon

Suzie and I have been working with teachers on pbl design for a while and we've hit on a new strategy. I'd like your opinion! As with many approaches, we start by having folks determine the Big Ideas of the disciplines they teach. They select several interrelated objectives and talk with others about real-life applications and interdisciplinary connections. In classic PBL design folks would now start planning assessment, determining what students would demonstrate to show attainment of new knowledge and skills. We skip over this momentarily to add an intermediate, iterative step we call the "project brief."

The project brief is the germ of an idea presented in a short paragraph (think 'elevator speech'). It gives critical friends just enough information to understand what kids will do and learn. It's intentionally brief so 1) the teacher doesn't get overly invested in a 'hard-wired' plan, 2) it's not overladen with procedural detail and is easy for a reader to digest, and 3) it's still malleable and can be improved or chucked altogether in favor of a better idea. If a teacher presents a brief that isn't clear he answers questions, gets feedback and advice, and works on it some more. Critical friends plump up a plan, advising on ways to strengthen the project.
Here are some project ideas we've helped shape . Some still need work. What would you advise?

We've used a simplified National School Reform Faculty Constructivist Tuning Protocol (pdf) for reviewing project briefs. Here's our version:

Project brief protocol

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The next stages, determining evidence of learning and designing the project more comprehensively, go along easier once a solid idea takes shape!