Three challenges in one song. Riders have three movement, speed or resistance efforts within each song. Intensity can start with easy, moderate or sort-of-hard for the first efforts (it will vary as the ride progresses), but the second effort is always at threshold and the third is above threshold.
For example, for Song 2, Shivers, you might have riders start at sort-of-hard for the first effort 1:00 Flat Road, then move to threshold (hard), to above threshold (harder); whereas for Song 8, Every Teardrop, you might have them at easy for the first effort 2:30 Flat Road for a working recovery before moving to hard and harder.
Let your riders know during the intro that they will be selecting their 3-in-1 for Song 9, All I Know So Far. That will give them a chance to think about their favorite combo before they get there. Enjoy!