Here are some ways to answer, depending on what you know:
If you know the teacher's origin:
* El profesor es de [País/Ciudad]. (The teacher is from [Country/City].)
If you don't know the teacher's origin:
* No lo sé. (I don't know.)
* No estoy seguro. (I'm not sure.)
* No tengo idea. (I have no idea.)
You can also ask for clarification:
* ¿Podrías repetir la pregunta, por favor? (Could you repeat the question, please?)
* ¿A qué te refieres? (What do you mean?)
Remember to conjugate the verb "ser" (to be) according to the subject (el profesor).