Well, as you can tell, I think it would take much more than money to fix the public school system. It would take a change in mindset in my opinion.
The school district I live in has recently purchased chromebook computers for every kid in the 3rd to 6th grade. I looked online and saw that many or most other schools have done the same. Since they're making it so easy to centralize teaching with this technology, why not begin running an incrementally larger part of the classes online to the kids and save significant money on teachers salaries? Not from home, but still in the classroom. It's all in place to do so right now it seems to me. Leaving aside the obvious objections from the teacher's unions, how does that sound to parents who have kids in school and people who are paying the taxes for it all?
The have the computers, so more of the classroom lessons could be taught online, right in the class. I think they already have most class lessons on video for about every subject. I would think it would result in more consistent quality instruction and less need for as many teachers.
This approach is called "flipping the classroom" and is the new modern approach to education being adopted by many charter and public schools in the U.S. The role of the teacher is changed in the classroom to being a mentor who goes around and helps each student 1-to-1 with their lessons rather than being an instructor who simply stands in front of the class reading the lesson (the videos provide the lessons now). This increased 1-on-1 instruction helps drive increases in learning and text scores. Note that most of the videos are created by the teachers who "flip the classroom". Some of the videos are available online from Khan and other sources. It is a fallacy to believe that this approach will reduce the number of teachers required in the classrooms. The same number of teachers are required, it is just their role in education is changing. I will also note that many homework assignments and quizzes/tests are now done online using services such as Blackboard. The teacher can also post information to these type of portals for the students to review.
If the teachers don't have to teach the classes, they should be able to handle more students per teacher. Regardless of whether one likes or dislikes this approach, at some point it may be forced to be considered. The gravy train of money printing to cover all needs is not sustainable in my view. Many think there will be a day of reckoning, Me included.
Actually the approach requires MORE teachers because of the amount of individual attention given to students requires more time. The New Schools Project funded by Microsoft founder Bill Gates which has been driving this approach actually recommends two teachers in each classroom (for about 30 students) rather than one. It's much less time intensive for a teacher to stand up in front of a classroom and read the lesson from a book & not care if some of the kids are not paying attention... and only have to get involved 1-to-1 with the students if little Johnny or Suzie is misbehaving. If you think this approach can be used reduce education spending then you are wrong - when applied properly it does not. However it does greatly increase learning when the technology and methodology is used properly. The issue today is that many teachers in the classroom (except the younger ones) are not comfortable with technology and using this approach. Generally schools that have effectively used the "flip the classroom" approach have younger teachers who are very comfortable with technology & computers. Unfortunately many schools think that if they simply give every child a tablet then they magically will transform their school - it does not work like that, you need teachers who know how to educate using the technology and make a strong commitment to "flipping the classroom".