My second child is suffering this in a UK school - the maths is too easy, his primary school had an 'advanced' group (quotes because it wasn't really advanced,

My second child is suffering this in a UK school - the maths is too easy, his primary school had an 'advanced' group (quotes because it wasn't really advanced, didn't go as far as I did at primary school in normal class) to push the most able kids a bit. Now high-school they're back to doing absolutely remedial basics of arithmetic. So much wasted time in school, he's frustrated not to make progress and bored with 'maths' (truly it's lack of maths, but to the young mind that gets confused with the subject and then you lose them).