I'm amused by the simple study that put a fraction of primary students into a gifted reading group. Gave them extra attention and feedback. After a year, that group had all advanced more than a year's reading skill.
Fascinating. ("The kids in the study who were given an opportunity to take more challenging courses that aligned with their skills and interests ultimately went on to accomplish more than the students who were not...")
It also says "This article originally appeared on 09.22.17." I wonder if there's been any new updates? The most recent one I found was this PDF from 2023.
The group was actually chosen totally at random.