A short update:
I did talk to DS last night about the proficient, advanced and perfect.
We had a lapse back into our montessori nightmare. To show proficiency at his montessori school he had to complete the entire workbook error free and neat enough to meet the teacher's dictates. If he missed 1 answer anywhere in the book or it wasn't up to her standards of neatness, he had to redo the same book start to finish. Hence, DS's belief that if he made a mistake, he would have to go back to the beginning again and that proficiency meant perfect.
Also, I while I couldn't get a clear answer from him about the idea that his teacher would lose her job, I think he was probably creating a frankinstein
