@Jerry - Sorry for being nosy, but I see you aren't a teacher, so I'm wondering why you're asking what "other" teachers' policies are. Did you have to cancel without giving notice, and you were wondering how your teacher will most likely deal with it?

I've taken hundreds of lessons here, and I only missed a lesson once where I couldn't give notice. The internet went out shortly before the lesson in that case. But the teacher was really nice about it, and offered to merely reschedule the lesson. I've had a handful of times over the years where I had to request to reschedule, and that's always worked out for us, although it sometimes took a few iterations.

That's an area where I've been very impressed with teachers here. There is no cutthroat attitude about collecting money when no lessons occurs, at least not in my experience. Teachers have been very flexible and generous with their time.

I imagine if you have a legitimate excuse, most teachers would schedule another time.

That being said, it's really up to each teacher as to whether he or she gives you a make-up class. Even if the student didn't show up for the lesson and it wasn't delivered, the teacher invested time in preparing for the lesson and then waiting at the computer for the student to show. If I were the student, didn't provide notice ahead of time, and had a legitimate reason, I'd ask the teacher if we could reschedule, but I'd certainly understand if they said no. 

I am not currently a teacher, but I did take teacher training, and teachers do spend a considerable amount of time preparing for a language lesson. Students don't see this as they only see what is delivered in the lesson. 

If either of us can't make the lesson (student or teacher), then we write a message as soon as we can. In Turkey, I was often caught out by sudden blackouts and couldn't message my student until a couple of hours later. These things happen!

The good news is, we're pretty understanding in general as long as we try to communicate. If my student (or teacher) hasn't turned up in the first 15 minutes of the lesson, I assume I won't see him/her in that timeslot and so I'll just log off and do something else. I'll wait for the message to come through later then deal with the issue then. Pretty much every time it's been a legitimate reason, so we just arrange another session.