School systems in general, specifically the United States' system, are awful. Some are better than others, with a rare few being rather good, but seeing as how I really only the US system, I'll be talking about that.
Public school is little more than a government run daycare system where children go while parents are at their job or busy with house work. The system of learning is using possibly the worst possibly method known to educators, but it's become standard. These days, it's all about testing. Pass this test, pass that test, do this exam and this quiz. And in all honesty, that equates to "cram for this test, hastily study for this exam". While the person can pass the test within the next two days, the knowledge retained is extremely low ... test them for the same exact material in a few weeks. Then, in most cases, the next subject is broached and the one previous hardly touched upon again. In short, our society values tests over knowledge.
How about yet another amazing shortfall? Our school system grants the students a break that lasts several months. That means any information that the student may have actually retained degrades over that time until it disappears from not being used (this is a scientifically proven fact that our brain will cannibalize parts of the brain's memory to make room for more recent information). When finally returning to school, the student then spends the first couple of months refreshing their memory about what they covered in the year previous ... an extremely ineffective use of time.
Not to mention how teachers are severely limited in how they can teach their students. A sort of 'blanket' method is used, which may work for teaching some people, but normally doesn't work very well with many. Each person has their own way of learning, so it only makes sense to figure out what a person's effective way of learning is at an early age (this is what the first few years of elementary should be geared towards).
And then of course our educators. Some are just terrible, others are brilliant. There really isn't a dependable and established system to detect when a teacher is no longer a positive source of learning ... some just give up and the students suffer. Either way, teachers are an integral and important part of our nation; the future of the next generation is literally dependent upon them. Yet, they have some of the worst pay and benefits. Oftentimes, they must buy the proper teaching materials with their own money.
I really could go on about all the crimes our nation imposes upon the education system ...