I think Stephen has provided an extremely wise advice to your case. Alan has also elaborated on further ways of bridging the gap between you as a parent, the teacher, and your child.
I think it may be necessary to refocus on what you and your child could do and achieve, under your and your child’s control, after considering all the advice and options available, rather than trying to fix the “perceived problems” which might be systemic (teacher’s problem, pedagogy (using Constructivism), or even about the school).
As for your child, you are the one who could provide him with the emotional support. There are certain educational values that you might like to educate your child, through this case opportunity. This includes an understanding of each others’ views and perspectives (yours, his teacher etc.) through conversation, and feedback. So, would a conversation with your child help? In psychology, some role plays could help in negotiation of solutions. For instance, if you ask your child to role play that of the teacher, and prompt him by asking why his teacher acted like that to his requests, then he may be able to understand why his teacher has responded in such a way, and what and where the problem lies. You could then ask for better methods in responding to such a situation, by encouraging him to think of different ways of solving personal problems and making responsible decision under his control. With your empathetic listening and mentoring, I think you could help him in gaining a better understanding of his needs, so he could then take personal responsibility of his belongings and learning.
There are many assumptions here relating to the approach in solving the problem, and so I think a connectivist approach would only work if some of the ideas suggested here by Stephen, Alan, me or others are considered in your own light, based on your understanding of your child, and a decision made by and with him, with a focus of helping him to develop further skills in problem solving and learning, rather than imposing a solution on him.
Here is my post on social networking and online learning. What are the needs of your son? That may be the critical question.
What would you suggest?