In the UK children do some GCSE subject around age 14 to 16. They get some choice of subjects such as choosing geography or history.<p>At 16, they have options. They can stay at school and do some A-level subjects of their choice. They can leave school and do whatever they want.<p>16 year olds can join the army, they can do a vocational course such as learning to be a cook, baker or a bricklayer. They can get a full time job, which in practise often means working for a family business because not many employers want 16 year olds.<p>Teenagers doing A-levels have a wide range of math knowledge. Some of them dozed through gcse math lessons and got a very low grade. Some of them learned geometry, probability and basic statistics.<p>One teacher trying to teach twenty teenagers who don't want to be there and where some can't add up three digit numbers and some can do algebra will be ineffective.<p>Children over 16, and their parents, can't be criminally charged or fined for truancy. Schools can threaten to throw them out, but the schools get money for each pupil.<p>There is not much you can do if 16 years old just don't turn up for math class.<p>If you tell the teenagers that hate math that they have to keep doing it if they stay at school age 16 to 18 then more of them will leave.