I recently took my high school general music students to visit and play on a historic tracker action organ, to get a first hand view of how classical organs work. I wanted them to be able to play something other than "Mary Had a Little Lamb" on it as they experiment with the sounds. I had each student learn a brief portion of the introduction of this famous toccata, or the whole introduction, depending on their comfort level. It was a lot of fun. Students only need a basic Treble staff understanding, and each part can be learned by rote if necessary. Some students who gravitate toward guitars or ukuleles learned part on those instruments in addition to keyboard.
This is my first offering. I hope you enjoy it!