Currently educational quality is based on the school students are forced to attend, which relates directly to where their parents live, which relates (indirectly) to the parents income.
Permitting school choice among public schools would permit parents to send their child (and the portion of taxpayer money that would be used to educate the child) to a public school of their choice provided that they take on transporting the child to the school. Overcrowding can be solved with a lottery or an admission exam.
This will not solve all of the problems of the educational system, but it will provide a more realistic economic incentive to force bad schools to go under and close while rewarding the good ones than our current test-results-driven system.