I have gotten tips but not in the form of cash except once. Usually they are in the form of being bought lunch, dinner, or I once got a gift card for a restaurant with instructions to take my wife out to dinner in appreciation of her allowing me to spend so much time away from her teaching. The one cash tip I got was after an OW class where I took one person into the pool for a 2 hour private session to work on specific skills. And that one came in the mail a couple weeks after the class ended. A bit hard to say no. But no they are not expected. And it depends on where you are as well. In some cultures if you do a job really well and the student decides to tip you refusing it can be construed as an insult. But to be honest the greatest tip is when someone calls and said so in so referred me to you. Can you teach me?