To answer, you need to know your classmate's name. Here are a few ways you could respond:
Formal:
* Se llama [nombre]. (His/Her name is [name].)
* Su nombre es [nombre]. (His/Her name is [name].)
Informal:
* [Nombre]. (Just [name].)
* Es [nombre]. (It's [name].)
Example:
If your classmate's name is Juan, you could say:
* Se llama Juan.
* Su nombre es Juan.
* Juan.
* Es Juan.
Remember to replace "[nombre]" with the actual name of your classmate.