Toucan [1] does something similar (but I think only at a word level, not sentences), so might be worth looking at what they do in terms of marketing.
Also, have you considered throwing in a spaced repetition component to the process? Really helpful when building an active voc.
[1] https://jointoucan.com/
Toucan [1] does something similar (but I think only at a word level, not sentences), so might be worth looking at what they do in terms of marketing.
Also, have you considered throwing in a spaced repetition component to the process? Really helpful when building an active voc.
[1] https://jointoucan.com/