Barney's friends are racing to clean up the park, but Kami has trouble keeping up with the other kids - even when they pretend to be ants marching in a parade! Barney and Scott visit the Idea Bench where Scott comes up with a great idea - to show Kami that even though the caboose is the last car in the train, it's the most important because that's where the conductor rides. With Kami playing "Conductor for the Day," they learn all about trains and have fun checking out a model train. Then, they work together to clean up the old caboose in the park as they sing "I've Been Working On the Railroad." When Barney tells them how railroad signal flags are used, the children make their own flags and wave them around the park. Barney's friends learn that from the first to the last in line, everyone is special.