Unit 9 is the first unit of my new experiment that I hadn't given any thought to last summer when I wrote this all out. It was one of those "I've done a lot, I can finish the rest as we go next year" thoughts that doom all teachers in the summer. As a result, much of the instruction in this unit has been direct because creating student-centered discovery lessons apparently takes a LOT of time and energy. That, coupled with a lot going on in my personal life has left me just trying to get by.
I'm at least still making every effort to demonstrate WHY the ideas we're discussing are true. No joke, the prepared materials that I was given when I started teaching were nothing more than: "This is the theorem, this is how it's used, now you try." No attention was given to the why & how questions, which is what led me to create this curriculum.
For secants, the main idea we're discussing is the relationship between the exterior angle and it's intercepted arcs. Similar to chords, but when the angle is outside the circle, we're looking for the difference between the two arcs, not the sum.
After a brief exploration demo, students were given the class period to work on U9 WS3.