How would you write a teacher doing roll call in a play script?

TEACHER

"Sarah?"

SARAH

"Here, Mrs/Mr ____"

TEACHER

"Ned, James, Ralf?"

NED, JAMES, and RALF stop their horseplay and quickly mumble affirmatives to their teacher.

TEACHER

"Walters, Valerie?"

etc

Basically just be careful not to overdo it. You don't want the audience to get bored. They won't care about the names until they have a big character or action to connect it to. You can choose, however, if you want Last,First or vice versa or even just a First name. It's all up to you.