On: Malawi app 'teaches UK pupils 18 months of maths in six weeks'

[turingfail]

There is the duolingo study: http://static.duolingo.com/s3/DuolingoReport_Final.pdf

I would interpret its table 11 as emphasizing the need for entertainment or other focus retention for success within a school curriculum. (I consider duolingo good at instant feedback but incapable of retaining focus without significant external motivation.)