Use proportional reasoning to make reasonable estimates
Understanding proportional reasoning requires students to consider a number or quantity in relative terms. With fractions, students must consider the fraction in context, such as one-half of a whole figure. Students use proportional reasoning to partition a whole into unit fractions.
A unit fraction is the base unit of any fraction and always has a numerator of 1; for example, 1⁄4, 1⁄15, 1⁄23 are all unit fractions. Every fraction can be decomposed into unit fractions. For example, 3⁄4 is 3 one-fourth units (so one-fourth is the unit fraction and we are thinking about 3 of them). Partitioning a model involves determining and creating a unit fraction.
Consider the fraction one and three-fourths. This number can be decomposed using a unit fraction.
One and two-fourths can be composed using a unit fraction.