5The teacher walked into the classroom, greeted the students, and took attendance.
Here we've more than one verb: walk-greet-take, but it's still considered as a simple sentence
No it isn't. It has three finite verbs. It is a compound or multiple sentence, as is the one below:
She is intelligent, they made her very famous.=
This is not even a soundly constructed sentence; it needs a conjunction or a semi-colon where you have the comma.
Student or Learner