About ten years ago, I began plotting a significant change in the physics curriculum at my school. My plan was to change our AP Physics B course from a first-year course to a second-year course. The reasons for this change are detailed here.
Briefly, AP Physics (B or C) is a second-year course. All AP sciences are second-year courses. Your colleagues who teach AP Biology or AP Chemistry wouldn't think of teaching their courses to first-year students. The College Board describes AP Physics as a second-year course.
Still though, many schools offer AP Physics as a first-year course. Why? The most frequently cited reason I've heard is that there's not enough time for students to take a two-year physics sequence. Well, there's not enough time for students to take a two-year biology or chemistry sequence, either. Nevertheless, those courses remain as second-year offerings.
We should encourage our most enthusiastic and gifted science students to complete a year of biology, chemistry, and physics, followed by an AP science course of their choosing.
The most successful first-year AP Physics teachers I've had contact with confess they do not do labs in their classes. What? A science class--a science class for the best and the brightest--with no labs? They assure me that they do labs--after the AP exam. The AP exam happens the second week in May. Most schools are out the first week of June. At my school, the last week and a half of school are devoted to staggered final exam schedule. So there's not much of a window, and I would suggest students are not at their best in that particular window.
Later I'll post some info about the consequences this change at my school.