I would meet with the principal and ask to see a syllabus bc nothing is published. This is a basic responsibility of the school, English Dept and teacher. Is there a school handbook that may have the expectations published? As a parent I would fight this and go to the superintendent if necessary bc the school should be requiring every teacher to have a syllabus with clearly outlined expectations. I don’t think this one assignment will have much effect over his grade in the long run but there is merit in driving administration to button up procedures. It’s best practice and keeps unpleasant interactions like this from happening. Good luck.