I could have written your post! My son started a Montessori preschool just before his third birthday. He struggled almost immediately. We switched to half days. He continued to struggle with the same issues as your son. Finally after a year and a half, we pulled him out.
I dreaded pick-up time. They would excuse the kids one by one from circle to do the hand shake thing and the teacher would give the parent a short report on the day. First, my son was almost always in the time out chair. As the kids were excused it would be "Katie did so well coloring today" and "Sonya is really working on her counting" and "Ben has the nicest art project to take home" and then we'd get to my kid "W didn't really participate much today. He wouldn't sit for circle so we sent him to the office. He came back and worked on some puzzles but when it was time for afternoon circle he wouldn't put his the puzzle he was working on away so he got a timeout. There was also an incident at recess. There is a report for you to sign. He threw sand at someone's face and it really hurt their eyes.". At this point my son would pipe up with "I didn't get SENT to the office I made the CHOICE to go there because I HATE your circle time. I threw sand because the boy was being mean and putting grass in my hair and he stepped on my sand building on purpose and no one would do anything about it. I had a really bad day and I want to go home"
