Oh Dear.....I feel your son's aloneness. Is he shy by nature? Would the teacher cooperate with encouraging some of the more caring kids to invite him in?
Some kids reach out and others wait for the invitation. You might also suggest ways it can invite himself to play with others. Try role playing with him or use puppets. You play your son so he SEES HOW IT IS DONE. Then he plays that role out so that he gets comfortable with it. He can also do a mental rehearsal where he plays it out in his mind and FEELS the rewards of socialization.
Let me know how it goes. Don't leave him alone. Social skills are a learned behavior that come more naturally to some. Hmmmm 2nd grade. Check out my character building program at www.wingsforwishes.com. He has CONFIDENCE building in it
and compassion so if his teacher plays the CD to all the students...they will be more sensitive to his needs. The program empowers and encourages kids and transforms lives....truly.