I’m a college student. My class has only 40 students. My professor left the classroom before class ended because, like he said, too many students were using phones while he was talking. It was not like there were phone sounds or the phones rang. He said before leaving that he would let us teach ourselves. 

In this case, I’m quite curious about something:

1. Would he be able or be allowed to not teach, and let us handle it ourselves and only come in to do the test?

2. Would he be able to fail the whole class?

3. Would he possibly react the same way if only 1 student used their phone without making any noise?