When I was in Elementary School many years ago, I got to go on a field trip with my class to a coal mine. The really cool thing about going to the mine is that they took our class into the mine where they work.
Since we were children, they explained what they did and this proved to be interesting. Of course it was more than we just mine for coal. As a child, the fact that I was in a coal mine and what the surroundings of a coal mine looked like was just incredible.
Learning about the coal mine was interesting and I did learn that no matter what job you might have, you are an important asset to that company.
Our field trip to the coal mine ended when we were given a piece of coal as a souvenir to remember our trip to the coal mine. I still have that piece of coal I got that day.