Trains are fascinating.
I imagine many of you as children have also stood alongside a railroad track and waved at the engineer as he passed. Or perhaps you pulled your arm down in a motion that signaled you wanted him to blow his whistle. One of my earliest memories is being taken down to the railroad tracks by my older brother so we could put pennies on the track. The weight of the train mashed them into wafers the size of half-dollars. Probably not something you need to teach your kids, but I did it anyway.