Few days break and dropped 1%. Why?
Have had a few days break for personal reasons. Before resuming note that my percentage has dropped by one. WHY?
The algorithm ages your familiarity, and puts the words with the longest interval since your last usage (see the Words tab where you can sort by when last practiced). The fluency calculation is some function of the percentage of the tree you have completed, whether each lesson is gold, and within that, when you last practiced each word.