The best teachers have teeth marks on their tongues.
Don't sweat the small stuff. Alfie Kohn is the author of these helpful books, among others:
Unconditional Parenting: Moving from Rewards and Punishments to Love and Reason: https://amzn.to/2HnjlJY
Beyond Discipline: From Compliance to Community: https://amzn.to/2qZGuHz
Punished by Rewards: The Trouble with Gold Stars, Incentive Plans, A's, Praise, and Other Bribes: https://amzn.to/2JlqtmU
The Myth of the Spoiled Child: Coddled Kids, Helicopter Parents, and Other Phony Crises: https://amzn.to/2r1U7Gi
The Homework Myth: Why Our Kids Get Too Much of a Bad Thing: https://amzn.to/2HVNTQ0