I’m a college student. My class is a small class with only 40 students. Today, my professor left the classroom before class ended because, like he said, too many students used 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 teaching, let us handle it ourselves and only come 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 use the phone without making any noise?