MOOC learners who posted in the forum passed at much higher rates than those who did not (57% vs 8% in one course), but the authors themselves call this a correlation under self-selection. Randomly adding a reputation system made replies more numerous and faster, with no difference detected in grades; an instructor replying actively versus not at all showed no difference in completion or engagement. No study has tested what a blog comment section does for readers' learning.
In a pooled analysis of 50 homework experiments on ASSISTments, hints, breaking a problem into smaller steps, and worked examples beat showing only the answer by d = 0.16–0.27, measured on performance during the homework itself. Interventions that worked in a few courses were scaled up to 247 MOOCs, and none of the main hypotheses replicated. Most course-quality rubrics don't publicly report reliability or validity; in one university's test, none of nine dimensions had a significant direct path to pass rates. The reviews of design-based research all look at how reports are written; none compares whether the materials it produces are more effective.
In a crossover experiment in a Harvard physics course, the class in which students scored 0.46 standard deviations higher on the test was the one they rated 0.56 lower; in an experiment with generative AI available, self-ratings rose more than actual improvement could explain. Viewing time, platform activity, and models predicting a pass mostly measure how much was done, not learning measured separately. This site's traffic statistics are aggregate, and none of its signals can measure whether readers learned.
In HarvardX and MITx courses, about half of registrants on average never entered the course; among those who did enter, only 3.13% passed in 2017–18. A prompt to write a study plan raised completion from 13.8% to 17.7% in three courses, but at 247 courses no difference in completion was detected. These are all MOOC numbers; this site's traffic statistics are aggregate, with no data on individual readers' behavior.