I have seen some subject ability grouping going on in our schools and they do test and change groups a couple times a year. They do not tell the parents when they are doing the testing, although they do not hide it either so I guess some parents may prep the kids.

None of the grouping in early elementary is high enough for a HG+ child, but it surely is better for an HG+ child to be in the top group than in a general group with kids of all abilities in terms of less boredom and maybe they are learning a little.

I have inquired about tracking/grouping in middle school years and it sounds like they do it to some extent but was not given a clear answer.