Relative has recently transferred from the US to yr 10 in the UK. Last report shows they are significantly struggling across the board but parents say its due to the difference in curriculum. I'm aware the curriculum in the UK is a bit ahead of the states but not sure how much especially if joining in yr 10 as a previously average student in the US.
Just wanted to get other experiences really from those who have been through it as parents are now thinking of bringing dc back to the US which I think is going to be further disruptive.