The document outlines 17 things the author wishes they had been taught in school. Some of the key lessons include: applying the 80/20 rule to focus on the most important tasks; using Parkinson's Law to avoid overcomplicating problems; batching routine tasks to work more efficiently; giving value before expecting to receive value; viewing mistakes and failures as learning opportunities; and maintaining a positive attitude to change one's reality. The overall message is that many useful life lessons are not taught in school but can greatly improve one's productivity, focus, and happiness.