Facebook founder Mark Zuckerberg made a bold statement in a recent essay: “If a student is at the 50th percentile in their class and they receive effective one-on-one tutoring, they jump on average to the 98th percentile,” Zuckerberg wrote. It’s a remarkable claim, one that strains the limits of belief. And for good reason: The results from the 1984 study underlying it have essentially never been seen in modern research on public schools.

Still, the results have become a popular talking point among those promoting the “personalized learning” approach that Zuckerberg’s philanthropy is advancing.

“If you’re really going to make these huge investments and huge pushes [based on this study], you might want to be absolutely sure that the analysis of that research is solid,” said Ben Riley, head of the group Deans for Impact and a skeptic of personalized learning.

The conclusions on the effects of tutoring from Bloom’s widely-cited paper are drawn from two studies conducted by University of Chicago graduate students. The applicability of these studies today is an open question. Combined, the studies focus on just three schools and a few hundred students. And since this was done more than 30 years ago,  things like traditional instruction may have substantially changed since then.

In sum, a number of studies suggest that Bloom’s huge results are not plausible to expect in public schools today, and they have rarely been seen in other research. Meanwhile, Zuckerberg, Shelton, and Chan Zuckerberg Iniative's (CZI) public statements imply that, with the right tools, students could see similar off-the-charts improvements.

Zuckerberg and his wife Priscilla Chan have pledged to donate 99 percent of their Facebook shares — worth an estimated $45 billion in late 2015 — to CZI over their lifetime.

Read the full article about personalized learning advocates by Matt Barnum at Chalkbeat.