The class is a team, a work team: the students and the teacher; they learn English together. I've learned many words when teaching.
The teacher helps students to learn by themselves, on their own.
Nonetheless the teacher is the main protagonist among the protagonists. He has to make presentations and explain the meaning of a word, first in English, afterward maybe in their L1.
The main source of activities? The teacher. He or she helps their students take the most from the textbook for instance. / Photo from: www usnews com