Finding Good School Districts

One area that perplexes me about california is how drastically the quality of a school district can change in just a few miles. The contrast is exemplified by the difference between Palo Alto, and East Palo Alto. These are literally bordering school districts on opposite ends of the spectrum. I was looking around today for a way to visualize where the good schools are located and found the following tool that displays all of the schools on a map with ratings:

http://schoolperformancemaps.com/ca/#37.431796%2C-122.131577%2C11%2C1

and more up to date info:

http://www.greatschools.org/