During Topic C, students build on their concrete work with composite shapes and begin naming equal parts of wholes, specifically halves and fourths (or quarters). Students more closely analyze the same composite shapes created in Topic B, recognizing composite shapes made from equal, non-overlapping parts and identifying halves and quarters within rectangular and circular shapes. In Lesson 7, students explore composite shapes that have been made throughout the module and sort them into two categories of shapes, those made from equal parts and those made from non-equal parts. Students count the number of equal parts that form one whole. Lesson 8 introduces the terms half and quarter, or fourths, to name two equal parts of a whole and four equal parts of a whole, respectively. Students learn half-circle and quarter-circle as the names of shapes, and recognize that they are named for their size and shape in relation to a whole circle. Models of rectangular and circular pizzas are used for students to discuss equal parts of the whole. In Lesson 9, students explore halves and fourths more deeply as they identify these parts within circles and rectangles of varying size and dimension. Students recognize that as they partition, or decompose the whole into more equal shares, they create smaller units.