I’m so sorry that your young son has experienced school trauma. I’m not sure my advice is going to be useful as we haven’t experienced the same, but I thought I’d at least reply and maybe something might be relevant. Please note that I am in Australia, so there may be differences in the education systems between countries.
In our experience, in the early years, the home is the primary source of learning, through informal chats about every and any thing, access to books and other learning resources (including in our household, unlimited access to the internet) and excursions.
I hope this won’t be discouraging, but we seldom found it useful to approach teachers to ask for our kids to be accelerated/extended. In our experience, teachers prefer to make their own assessments of the level of each child’s capabilities. To do so, some of them have said they gauge kids by raised hands when they ask questions, so even if seldom picked, encourage your child to raise their hands whenever they believe they have a correct answer. I was incredulous when my eldest’s eighth grade maths teacher, despite my daughter having been first in every single exam and test (with perfect or near perfect scores), commented that she never knew if my daughter understood the content taught in class because she never had her hand up.
Whilst we quickly learnt to stop making demands of teachers and the school, we also supported our kids not to have to do ‘busy work’ that provided no learning value or stimulation. I politely and firmly stated this at parent-teacher interviews. This resulted in positive negotiations whereby my kids were ostensibly engaged in the same activities as their classmates, but we were able to substitute the content - for example, my son who mastered the multiplication tables early in kindergarten, was given the same multiplication sheets as his classmates, but he completed his exercises in Roman numerals, binary and in different number bases. For spelling, he could choose his own twenty words each week to complete the same set of activities - master the spelling, learn the definition, use in a complete sentence. He chose the most obscure words from the dictionary. The teachers were happy with these arrangements since they did not need to put in any extra effort for lesson preps and the whole class was engaged in harmonised activities.
Best wishes for your son.
