14:22
@M.A.R. You mention of TPRS was the first I've ever heard of it (but I am not in the language teaching business so there's that).
Looking it up, I am of several minds about it.
1) the progressive learning -in the language- with no explicit grammar teaching, is a commonly refound technique. Berlitz is famous for it (late 1800's?). On speed of acquisitino of a foreign language there's been lots of research, where for phonology (speakng without an accent and hearing all phonological distinctions, is easy before puberty, but takes many years of training -after- puberty.
But for syntax and vocab, one can be fluent in formal speech (almost moreso than native speakers), but that also takes a lot of higher education. I don't know the research on comparing different methods, but my guess is that there's no appreciable difference, and that most of the success in learning is with a) motivation of the student and b) availability of materials (books/media).
as an aside to the grammar vs no grammar, for adult learners, I feel like it would be impossible to get good grammar in the foreign language without some knowledge of the rules that are different, otherwise it is way to easy to do mental word for word translation in order which just sound awful in the new language. Doing -all- grammar is obviously a problem, but the 'burn it all down' mentality is not helping.
2) It sounds like the TPR of TPRS was rebranded from some bullshit aromatherapy horoscope scientology thing (Total Physical Response) to a fairly anodyne but reasonable method (Teaching Proficiency through Reading). I can't tell if the reasonable method still has anything to do with the older movement.
3) The Ørberg method that @Cerberus mentions I've only seen in Ørberg's Latin learning books. I really like it (I am halfway through 'Familia Romana' right now) but I've had intro to Latin and lots of French and Spanish (B1 and A2 respectively) so I am able to pick out a lot of the vocab without having to spend too much time with a dictionary/google translate). But the experience makes me wish all languages had such teaching texts.
It's very methodical - each chapter is a little story (2-4 pages), introduces by example a handful of vocab, a new grammar piece (eg agreement of adjectives and nouns). It's all -in- Latin. Usually the new vocab is explained -in- Latin.
If it were in English it would be awful exposition because sometimes sentences are repeated but in slightly different ways or a paragraph from another character's point of view where the language eg "John hit David at 3pm. David was hit by John in the afternoon".
But that's exactly the thing that would be great for a language learner, the small repetition of slightly different things.