[notahacker]

> For (ii), every exercise or review sentence has a link directly back to the source material. I am playing with the idea of extending the context to +/- N sentences when showing an exercise as well.

This would be a good idea, but my point is more that content in general writing (as opposed to specifically constructed to be self-explanatory writing) is inferred from structure and callbacks to the words or tone of much earlier sections of the writing. Language learners do have to handle passages of text which aren't written with ease-of-comprehension in mind, but they don't have to try to fill in the blanks for "As seen in the previous chapter, x is an example of ______" without reading references to x in the previous chapter first. That's often an impossible task even for native speakers. Similarly, people are much more likely to correctly guess at meaning of a word describing a characters' emotional state (or internalise the meaning after looking it up) if they followed the narrative of the section six pages earlier which provided the context for their emotional state. Not stripping that context, or algorithmically isolating the sentences in a piece which don't require context to fully understand is a tough challenge.

[solarmist]

Ah, okay. I understand now.

Yes, that can happen, but from my experience it is rare; Also because this is focused on learning the language I can give hints/affordances like the word, or definition, in their native language, so all user needs to do is produce the word in the target language and conjugation.