In no specific order, and by no means a complete list -
- apathetic kids that have no interest in school
- apathetic parents that have in interest in their childrens schooling
- far too bloated operations/upper level positions
- poor spending of money (largely due to the above)
- *some* very poor teachers
- lower caliber of talent vs. other career fields (why teach when you can make 2x-10x the salary in the private business sector?)
- increased regulations and stress of offending someone leaving teachers with their hands tied
There is no single reason why schools are "failing". I personally think that smaller schools (200-500 students) offer a much better education than large schools (1000+ students). It's been my experience that students who came from a small town school are more well rounded in their education, have better work ethics, and are better prepared for college. Most of the problems that I hear about school districts "failing" are from larger schools in larger cities.
I dunno, maybe I'm naive, but that's just what I've witnessed.