Tiny
Your initial question was about how you could prepare for the class was not answered.
The class consists of two main parts, which are:
How to teach, and
The material that you will teach.
Other than reading and rereading the NRA student books,
which the instructor should have sent you prior to the class
there is not much that you can do.
Someone suggested that you practise by teaching your friends or family.
I think that this is a waste of time, since you know neither the NRA way of
teaching, nor the material that the NRA wants you to teach