Mail Time: I love the AP Physics 1 Workbook. Why isn't there a physics 2 or physics c workbook?

If you teach AP Physics 1, I hope you've discovered the Workbook.  It's great.  But, the question was asked, why only for Physics 1?  Why not provide the same sort of scaffolded, sequential, task-modeling exercises for all physics courses?

There's not a Physics 2 or C workbook simply because of the necessary person-hours - and high-end expert person-hours at that - required to produce the book!  Amy Johnson, who's as expert as you'll meet, spent a truly ridiculous amount of time spearheading that project (and writing much of it herself).  

Then, AP Physics 1 was prioritized because that's the largest and hardest course, the one where it's rather commonplace for a school to tell a biology teacher "oh, you are certified in science, you can teach AP Physics 1, good luck."  I've met so many of these unfortunate folks.  They often become outstanding physics teachers!  But in those first couple of years, they need an anchor.  

The workbook can be that anchor.  While it's in no way good practice, it is nevertheless possible for an overwhelmed and inexperienced teacher to do nothing but assign the workbook, page by page... and their students would have a fighting chance of success in the course.  Then the teacher can build on that foundation in future years.  

And finally, P1 is the most misunderstood AP course.  "1 - Algebra-Based" conveys a sense of simplicity to nonexperts, such that administrators and parents and amateur college counselors routinely push weak students into this course, expecting an easy STEM AP credit - yet P1 is, statistically, the most difficult AP course of all.  Teachers don't always know better, either: so many assign Giancoli calculational problems, teach nothing beyond plug-n-chug, then are surprised and sour-grapes-y when few students pass the exam.  

The workbook is there to demonstrate the kinds of verbal responses that will be necessary on the exam; and to guide students (and teachers) toward building the necessary communication skills.  For strong students, AP C can be picked up from textbooks and Khan Academy-style videos.  Physics 1 isn't so easily mastered, even by top-rate students.

Hope that helps explain... Really, the physics folks involved with the College Board are trying to help everyone.  They ain't perfect, and they can't please everyone, but they're trying!  :-)