According to the original words in the textbook, that is to say, the number of willows is regarded as the unit of 1. What are the three fifths of the unit of 1 now?
This is to let children understand the difference between three-fifths of the number of willows and three-fifths of a willow. The difference is that three fifths of the willows take the total number of willows as the unit 1, and three fifths of a willow take a willow as the unit 1.