My opinion of evaluations: Do what you would normally do in the normal manner you would do it and you will do fine. Less stress for you and an honest picture of what your teaching is like.
As for instructional level, think about the students you will be teaching. Do you think they are where a second grader should be in their musical knowledge? Are they above it or below it? I assume you need to give a written response so just discuss this. I am not a Music teacher so do not know how to assess this and if you have not you most likely will not be able to by your eval so don't worry about it. Go with your gut, but justify it with examples. You might mention the resource kids and how you modify your lessons for them. Administrators love that kind of stuff.
My mom is a music teacher and she says admministrators do not understand music teaching anyway so she does not worry about it. Does her thing and moves on.