From Lant Pritchett’s Rebirth of Education:
In 1976 in Nicaragua, the government tried out broadcasting lessons over the radio. This innovation was evaluated using a randomized, controlled trial to scientifically test the learning gains of students exposed to the radio-based instruction versus those who were not. The study, published in 1981, proved conclusively that radio-based instruction was more effective in absolute terms than traditional classroom-based pedagogy and was wildly more cost-effective.
So the end of the story was widespread adoption of broadcasted lessons, followed by improved average test scores in Nicaragua, followed by adoption and adaption for other places in the world, right? Wrong. Radio-based instruction did not meet the standard of isomorphic mimicry—it didn’t look cool. The cool, richer countries in the education world didn’t use radio-based instruction, so why should Nicaragua? Of course, Nicaragua soon thereafter entered into a long period of civil war and political strife, so the counterfactual of what could have been is impossible to predict.