Hi Robert,

1. There's not a way to hide or restrict access to the course content (all users are able to access all of the courses and all of the content within them), however you can assign individual pieces of content that you would like your students to complete. Assignments can be given to all students or to individual students. Here are some instructions for creating assignments.

2. Unfortunately we don't have a general placement test available, as in an all-encompassing math placement test, but you can use the Unit Tests and the Course Challenge within a specific course as a substitute. This will give students credit for the skills that they are already familiar with, and will also recommend skills that they need to improve on.

If you're new to Khan Academy, I suggest taking a look at this article on Course Mastery to gain a better understanding of the overall course structure and mastery mechanics used by our platform. We also have a quick crash course for teachers that covers all of the site basics.

I hope this helps! Please let me know if you have any additional questions!