2. A method, implemented in a computing system, comprising: assessing a user's comprehension of a plurality of target foreign language words corresponding to a plurality of base language words; producing, in response to the assessing, a mixed language text based on a base language text, the mixed language text including a foreign language word from the plurality of the target foreign language words substituted for a portion of the instances of a corresponding base language word from the plurality of base language words occurring in the base language text, the producing performed in processor; and presenting the mixed language text to the user.
13. The method of claim 2 , wherein the assessing includes determining a datum associated with the user's comprehension of the plurality of target foreign language words, the method further comprising: receiving a user request to repeat a portion of the mixed language text presented to the user; and updating the datum based at least in part on the user request.