Welcome!
Just a couple of quick thoughts:
1. Do you think you can get your son's first grade teacher to the meeting? She might be able to provide additional support to you and/or suggest a method or two (to the new math teacher) on how she was able to teach DS despite "immature" behavior.
2. Get everything in writing! If there is no official documentation, send a follow-up letter/note to each person who was present at the meeting. "Just want to say thank you for your time.... just want to make sure we are on the same page.... this is my understanding of our discussions...." etc.
Hope this helps and good luck!
Mag
