All the advice you received looks to be solid. The only thing I would caution you about is the direct contact with his teacher. I suspect the teacher will be on the defense immediately because if your son did in fact not meet deadlines and the teacher did not attempt to communicate this with you, he/she will be a fault and he/she will be covering his/her @ss. This is why I 100% agree with the detective role ... take emotion out of the equation. Go down a list with the teacher and expect the results: ie. grades, assignments he didn't finish on time and how late did he turn them in. Also is this a recent situation or has it been going on all school year. One question you should definitely ask is if the teacher attempted to contact you. They might argue they did by sending a note home with your son, but no matter how many notes were sent through your son it isn't direct contact attempts with you. Did they attempt to call or email you? This is the information you need to gather. Then and only then would I contact the principal and talk to him again because now you have the full picture. And absolutely research your state and district requirements and rules. If you provide more info, I'm sure you will have some help on the research front from this board.