Twenty Percent Learning Disabilities?

Back.....WAY back.....in time, when we attended a grade school (heated by burning wooly-mammoth chips), the incidence of "learning disabilities" was about zero.

There were kids who did not WANT to learn, and those who learned slowly. They fit into the typical bell-curve. Some did well, some did not, most did OK.

Now we read this:

The researchers surveyed samples of parents from both groups and reported that 18.2% of the MPS parents said their children had learning disabilities, while 8.7% of voucher parents said so.

(This was the research used to establish "baselines" in comparing MPCP with the MPS.)

Near TWENTY PERCENT of MPS kiddies are "learning disabled"?

We all know that "LD" means "extra revenue" for school districts, so there's an interest in establishing kids as "LD".

One wonders what, exactly, constitutes "LD"?