The Chapter 70 formula: "actually quite simple"

I've now been sent this twice (over and above getting it myself), so apparently, it needs a post!
While I'm the first to be entertained by finance people who earnestly tell you that something is "actually quite simple," kudos to Mass Budget and Policy Center for giving it a great shot!
They've boiled it down to four steps:

STEP 1: CALCULATE FOUNDATION BUDGET

this is basically "how much does it cost to educate a kid in X community?"

STEP 2: CALCULATE REQUIRED LOCAL CONTRIBUTION

Of that amount, how much can X community afford to pay towards it?

 STEP 3: FILL THE GAP WITH CHAPTER 70 EDUCATION AID

Take amount 1, subtract amount 2, and you've got Ch. 70

 STEP 4: AFTER CHAPTER 70 AID IS DETERMINED, DISTRICTS MAY CONTRIBUTE MORE

 Ah, yes...the over and above...this is seldom seen in Worcester. Check out the chart they give comparing Lynn to Newton. 

The second page, which gives the updates on Ch.70 since '93, is where things get complicated. Little known, for example, is this: 

If the Chapter 70 formula were run in its simplest form, according to the four steps outlined above, some high-wealth districts would not receive any state aid to fill the gap between their foundation budget and their local ability to contribute because for these districts their target local contribution, based upon local property and income wealth, is actually higher than their foundation budget. Since the formula’s establishment in FY 1994, however, there have always been provisions guaranteeing some base amount of state education aid to all school districts. The 2007 reforms increased this base considerably, shifting a greater proportion of state resources to these higher-wealth districts.

Give it a read. Not light reading for Friday, but well worth doing.