Am fascinated and have some questions - as someone who is a parent helper twice a week at a primary school
Everything that happens in the classroom, and school, is totally confidential.
totally agree
Don't help any child who has an accident with their clothes with getting permission from the teacher first. This may sound harsh but even changing socks on the wrong child can summon up a heap of unwanted paperwork and issues. I would never do anything with regard to changing but we are regularly asked to help with coats - would you feel this was ok?
Don't discipline the children. in what way? I tend to ask them if they feel that was behaviour that Mrs&^ likes in her classroom? would that count?*
Don't share your observations of the other children with the teacher. I don't really do this unless someone looks significantly less happy than other days I think it is important that it had been noted
You are really looking to be across between an invisible pair of hands and a lovely friendly person who doesn't make the teacher feel threatened or over protective over the children.
Don't look at the teachers notes or records. totally agree
Do what the teacher has asked, even if you think you have a better idea.
Don't expect to be left in the classroom alone and unsupervised. I am regularly the only person in the classroom only for a few minutes at a time but the indoor outdoor time can mean that I am often the only adult in one of those area's
i would add to the OP, enjoy, and remember what an amazing opportunity it is to watch them learn so much in such a short period of time 