There is a movement nowadays to teach children and later teenagers about money and give them a financial education, so that they don't make stupid mistakes with their money out of lack of knowledge.

But what people need even more is to become aware of how important time is and how to manage it well. I know, as a child, teenager or even young adult, this is not something that seems like a priority... since you've got so much of it. Much better to have some fun! And it is, but later you may end up regretting the wasted weeks, months, years, since time is irreplaceable as your teacher very well told you. Very considerate of him/her to tell you guys something so important about life when you were a teenager. It's true, as you said, only later in retrospect you understood what he/she meant. Maybe few teenagers would really understand this at that age...