教室でどうどうとタバコをすう高校生たちとそれを注意できない教師たちは罰を受けることになります。

。

High schoolers who brazenly smoke in the classroom, and teachers who can't correct them, will both be punished.

Literal

Classroom [at-で] brazenly tobacco [object-を] smoke high-schoolers [and-と] that [object-を] cannot-correct teachers [topic-は] punishment [object-を] receive [thing-こと] [will-become-になります].

School policy announcement. どうどうと ('brazenly, openly, without shame') is a mimetic-adverbial for unashamed, bold behavior. 注意する ('to correct, to admonish, to warn') is the standard verb for a teacher's corrective intervention. ~ことになる ('it will come to pass that X, be decided that X') marks an administrative/consequential outcome. Both the students and the teachers are the subject of punishment — interesting dual accountability.