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This is probably easier for heavily procedural subjects, like math and meditation. Note that math instruction is already a lot like this, and doing exercises feels like "sitting down to do math".
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That suggests to me that it's not the app format but the procedural nature of the domain. Sitting down to meditate or to do math is easier, and is straightforward to offer in app form. See also a million popular exercise apps. But how does one just sit down to do history?
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For history Anki + engaging videos + discussion groups should be more than enough in my opinion. Teaching and learning math, physics etc. is more difficult than teaching or learning history.
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