The big ideas in this unit are partitioning and unit iteration. We are very familiar with partitioning. For fractions, partitioning is again just splitting the whole unit into equivalent parts. (illustrated below) Partitioning is best used when you start with the whole unit.
Unit iteration is just as useful and common as partitioning, although it's not as obvious. Unit iteration is consistently repeating a unit to build a whole. (illustrated below) This method is best used when you only have part of the whole.

