16. The processor-readable medium of claim 1 , wherein the code representing instructions configured to cause the processor to produce a plurality of mixed known language-foreign language streams includes code to dynamically produce the first known language-foreign language stream based on individualized proficiency data associated with the first user.
1. A processor-readable medium storing code representing instructions configured to cause a processor to perform a process, the code comprising code to: deliver a video presentation simultaneously to a plurality of users; produce a plurality of mixed known language-foreign language streams, the plurality of mixed known language-foreign language streams including a first mixed known language-foreign language stream having a first grammar syntax and a second mixed known language-foreign language stream having a second grammar syntax; and deliver simultaneously the first mixed known language-foreign language stream to a first user from the plurality of users and the second mixed known language-foreign language stream to a second user from the plurality of users, the first user having a proficiency different than a proficiency of the second user, each of the plurality of mixed known language-foreign language streams corresponding to the video presentation.