Answer: If you feel your instructor has delivered exceptional service, then absolutely. As in any service industry, please do so only for exceptional service and base your gratuity on your level of satisfaction.
If you wanted to leave a tip at the end of the lesson but didn’t have cash that’s okay because if you really want to leave me a tip you can send me money using Google Wallet. Just go to Google Wallet, enter my email@example.com email account and type the amount you wish to give me. It’s that simple!