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Pulling my kid out of kindergarten(r/Parenting)
Pull him out and talk to the principal, definitely. Others have suggested observing to see how he really acts, but at this point you won’t be seeing how he “really” acts; he’s been marginalized and excluded to so long he doesn’t have a healthy relationship with the class, the teacher, or the school. It is no wonder his behavior got progressively worse.
That said, I’d like to focus on one other thing. You’ve probably realized this by now, and of course hindsight is 20/20, but you ignored a whole load of signals your kid was giving you that something was wrong. I say this not to blame, but to note that your kid deserves changes at home in addition to school:
You didn’t follow up in the attitude changes, the sudden insecurity, or the anger at pickup time. None of your communication at home tracked down this major issue. You even flat-out refused to trust him at one point, to the degree that he felt the need to please you rather than tell the truth: >I keep insisting, “That’s not really your desk, is it? Which group do you sit in?” And eventually he takes me to one of the group desks.
Use this as a sign that you need to improve your communication skills with your kid and be more aware of the signals he’s sending you. I always recommend How to Talk So Kids Will Listen & Listen So Kids Will Talk; I found it to be incredibly helpful.