The idea that their is no alternative, or workable alternative, kinda mooted in the other thread by
Shippou-Sensei , is laughable and wrong. It's not like we (UK) have always done it this way or that other countries don't do things differently.
There is so much that can be said but I'm not going to even attempt to put it all in one post. I'll start with some basics.
Thora said start formal education at 6. I'd go one year further and start at 7. I was at school a long time ago as a pupil but even then I always had the idea so much time was wasted and we were forced into formal education too early. Britain is one of the earliest starters in the world. Finland starts at 7 and has one of the best education systems in the world.
Those pre-school years don't have to be idle, but they certainly don't have to be formed by putting a pen in a five year old's hand and telling them to do sums. Again, in Finland, much emphasis is put on creative play for these ages. Learning how to socialise, learning how to adapt to their environment.
We test too much. I think we may formally test more than almost any other nation. There is no need for this. Get rid of all formalised testing. Train teachers to an exceedingly high level so we can rely on their expertise to summarise a child's development. That will tell you more than any pen and paper test every year or two that is largely based on memory.
Stop teaching subjects in abstract, isolated terms like separate units that have nothing to do with the other separate units they learn. Teach by topic and by theme. Engage the kids. Give them a voice in the topics and the themes. If they walk into a class that has to some degree been chosen by them they are far more likely to engage than in a cold topic of 'Maths' or 'History'. See Donaldson. See phenomenon-based learning.
Treat vocational education with the same importance as academic qualifications. Teach it alongside the curriculum. Start proper vocational based training and education at 14. Involve outside agencies and employers. From that age. Bring back proper apprenticeships. Give them status. Let that vocational based education count just as much as formal academic education by providing higher education establishments that recognise this and allow students to specialise and be professional. Don't just chuck kids into 'college' without really meaning it. Make those colleges have the same status as any other higher education establishment.
Stop testing. Give kids a voice. Give them a chance to engage. Appreciate all skills equally.