How do I know which courses fulfill which parts of the requirement?
Consult Chapter IV of the Yale College Programs of Study. Each course that fulfills some part of the Foreign Language Requirement is designated L1, L2, L3, L4, or L5, telling you which part of the requirement that course fulfills. If a course listing indicates "L1-L2" (or "L1, L2"), it means that course, if completed successfully, fulfills both the L1 and L2 components of the requirement. (This designation appears on year-long courses as well as on one-semester intensive courses.) Likewise, a course designated "L3-L4" (or "L3, L4") fulfills both L3 and L4, and "L1-L4" (or "L1, L2, L3, L4"), which appears on the listings for some intensive courses, means the course fulfills all four. Keep in mind that a designation of "L5" can appear on many courses above the L4 level. Not all L5 courses are equivalent in difficulty, however. Some are designed for students with greater proficiency and may have additional prerequisites.
These designations can also be found in the Online Course Information (OCI) system. However, for your results to display the L1-L5 designations, you must click the "New" button in the distributional requirements box on the search page.