Biliteracy is the ability to communicate with a high level of skill in two languages. Biliterate communication requires the student to have the capability to read and write another language, as well as the ability to listen to and comprehend (or speak/sign) the second language. The student must have the ability to use culturally-appropriate language to communicate spontaneously in non-rehearsed contexts with a high degree of competence, in real-life situations. Because language ability is not static and deteriorates over time, especially if the student is not actively using or learning the language, the testing window to demonstrate that proficiency opens only 15 months before the expected graduation date.