All kids dabble in stretching the truth or outright lying, and of course it's to their benefit to learn that lies have consequences. To be clear, all kids lie at one point or another. I know you may be thinking yours has never lied to you, but if so you're in La-la-land. Once you've come to grips with this truth keep reading.
Teachers need to understand that they are held to a higher standard than other professionals. It is difficult sometimes to discern what is and is not appropriate behavior. I once heard a gentleman tell new employees that you're a teacher 24/7. When you're hired, you're representing the school district all day, every day, and you fall under the ethics that entire time.