Aloha there Daniel,
We also use Moodle for a K12 public school district. Most of the secondary courses the teachers have their own courses. However when we implemented Moodle for the elementary student, we realized that it probably would be more efficient to create a single course for multiple teachers. Sort of a safe way to introduce Moodle to the elementary teachers to using a LMS before training them how to create content. This has been successful because the teachers are gaining experience using Moodle to have students do independent learning activities along with monitoring their students progress.
We only use Restrict access to release activities by date or activity completion so that the students are not overwhelmed when navigating the course. I am not sure if this idea will work for you because, we created the content and the teachers are using the same exact course with all the students doing the same learning activities. The teachers are not adding their own activities or resources yet.
What we found that works for us is to change the common module setting group mode to separate groups. That way when you follow Mary's instructions how to limit the teachers to their own students. So when each teacher looks at the activities that their students completed or progress, they will only see the results of their students and not ALL the students. So this works great for us, but our teachers cannot add their own learning activities yet because they are limited to non-editing teachers role.
Once the elementary teachers build a comfort level with teaching with Moodle, we will introduce them to creating content and will cross that bridge when it comes...