In my fifth grade class there was a boy that combined a most vivid imagination with an encyclopedic knowledge of speedboats. He would squat in his chair, hands up at the steering wheel, providing the sound effects for his cruise through the bay of his mind.
Our teacher would call him back to chalkboard words, calling his name, but never telling him to stop. She would ask him to please bring his boat in and park it at the dock. The rest of us would listen as he revved his motor, slowed down as he approached the classroom coast, and reversed perfectly into his spot before shutting off the ignition. Now he was back with us, and ready to learn.