This is the 1822nd most frequent Chinese word.
课堂
Classroom; class session.
The word "课堂" refers to the physical classroom environment and setting where teaching and learning activities are occurring.
课堂上，学生们正在认真听讲。
In the classroom, students are attentively listening to the lecture.
Here, "课堂" is used more abstractly to indicate the discussions and activities associated with the class environment within the course.
这门课程的课堂讨论让我受益匪浅。
The classroom discussions in this course have been extremely beneficial to me.
In this sentence, "课堂" signifies the concept of the classroom but applied to a virtual or online context.