I just came across this today. No way. This just can't be true. Progessive educators do themselves no favors when we cite "studies" such as these. Yes, I totally agree that doing and teaching others will lead to greater retention than listening to a lecture. But isn't one at all suspicious but the neat increments of increase this chart shows?
I did I bit of digging and found this article. It seems my hunch was right. I wonder how much received wisdom is equally questionable.