Until the eigth school in the list, they’ve only included schools with a few students which means that any large percentage drops or gains are not strange at all, but expected. To put them on the “Biggest Metro Math Losers” (what kind of name for a table is that anyway?!) is simply poor reporting.
I’m sure the editors would think a reporter insane for doing the same thing for the baseball box scores: “Mauer was 2 for 4 on Tuesday, but only 1 for 5 on Wednesday. That’s a 30% drop!” –IB –Newspaper Reporting (Three Standard Deviations to the Left)
The big problem here, as IB notes, is that the article in question deals with a very small pool of students, so that normal fluctuations in the numbers look like huge drops and gains. (Thanks for the suggestion, Josh.)