备课 (bèi kè): (of a teacher) to do one's lesson preparation

Since she has to teach a new lesson tomorrow, Mrs. Li stayed in the office preparing her lesson until ten before going home.

Mr. Wang is especially careful in preparing his lessons; he revised every slide three or four times.

Teaching this course for the first time, she spent the whole weekend preparing lessons and also asked experienced colleagues for advice.

Mr. Zhang gets up early every day to prepare his lessons and writes down all the questions he plans to ask that day in his notebook.

Because an extra class was added in the afternoon, he spent his lunch break preparing for it and didn't even have time to eat.