"slow", "rough", and "expoScale" eases are not in the core - they are packaged together in an EasePack file in order to minimize file size. "CustomEase", "CustomBounce", and "CustomWiggle" are packaged independently as well (not in the core). See the installation page for details. Easing is the primary way to change the timing of your tweens. Simply changing the ease can adjust the entire feel and