Right, let's just forget the fact that the tools aren't the real problem; the people are.
What is the definition of a tool? "Anything used as a means of accomplishing a task or purpose." What is the task or purpose of a gun? To kill. Guns enable people to kill more easily and in greater numbers than any other tool. Firearm murders make up 60% of all murders. Guns are the real problem.
Think about the mentality of the age group you are thinking of. You are immediately assuming that high schoolers - the group that already assume they know everything there is to know about life, the universe, and everything simply because they are fast approaching adulthood - are the group to teach about what a gun does to a life, regardless if it's human or not.
So you're advocating guns on an elementary school campus?
Are guns required to be involved in such a lesson? Outside of the tool/toy lesson, perhaps not.
Or are you just saying that teachers should be the ones to raise kids, instead of their parents? If so, I've got about 65 dependents I should be able to claim on my taxes in a couple weeks.