Good luck, and happy teaching (and learning).
Notice that a good answer key doesn’t just give the answer; it often provides a in the margins (e.g., “ since requires present perfect”). This turns grading into a teaching moment. New Headway Intermediate Test Answer Key
A: For speaking and open-ended writing questions, there is no single correct answer. The key provides possible answers. As long as the grammar is correct and the response is logical, you can mark it correct. Good luck, and happy teaching (and learning)
If you are studying independently without a teacher, finding the answer key can be tricky. Legitimate options include: New Headway Intermediate Test Answer Key