This morning I spent about 25 minutes learning an Irish jig called Behind the Haystack using a video from Mandolessons.
The piece has a ternary form: A - B - C, where each of the parts reuses the same endings. So the form looks like (E1 = ending 1, E2 = ending 2):
A - E1 - A - E2 - B - E1 - B - E2 - C - E1 - C - E2
I really like the sound of this kind of music, particularly on the mandolin. It has a beautiful sway and lilt to it. What is fascinating is how easy it is to know how long any given note is in relationship to the ones around it without ever seeing the music. Learning by ear is really remarkable.