I sometimes tell my students that my kids (ages 7 and 5) could teach some aspects of the course: don't steal, don't take what's not your etc. Here is another simple lesson I have already taught that my kids: if you realize you made a mistake don't lie to try to cover it up, it will only make matters worse. Instead, admit it and try to find a way to fix it. Try to minimize the consequences if possible but ultimately accept them and learn your lesson from the experience.
Here is a new case that illustrates this. The Legal Profession blog is reporting that the Massachusetts Supreme Judicial Court has ordered a two-year suspension in a case where the attorney had committed negligent misappropriation. In response, the attorney made false representations to Bar Counsel and submitted false documents to support his explanation.
Note that the charge here was based on negligence. That is significantly different that cases where the attorney knowingly tries to steal money from clients. The attorney made a mistake; an important mistake, clearly, and a mistake that would have consequences, but there is no question that lying about it made it worse.