My DD6 is going through something similar now in 1st grade. She sometimes plays with her classmates, but her best time in school was back in the fall when she hooked up with a few 3rd grade girls and collected worms in the playground. It's clear she hasn't really connected with any of the kids in her class. I've asked the teacher about it, and she says that DD just talks on a different level from the other kids, and they don't seem to get her a lot of the time.
Have you talked to the teacher to find out what kinds of interactions your son has with his classmates? Does he try to engage them but is rebuffed? Does he tend to go off and ignore everyone? Is the fact that he's in an immersion program a possible issue?
Our solution is...we haven't found one yet that doesn't involve pulling her out of school.
