Topic C reinforces the measurement concepts and skills learned in Module 2 while focusing on customary units. In Lesson 14, students use an inch tile to measure various objects using iteration. By connecting to prior learning, students deepen their understanding of a length unit, seeing again that just as it was with the centimeter cube, the length unit is the distance from one end of the tile (or cube) to the other or from one hash mark to the next. In Lesson 15, students create inch rulers using the same process as they did in Module 2 to create centimeter rulers, using the mark and advance technique with inch tiles to record each length unit with a hash mark. Whereas in Module 2 students made rulers 30 centimeters long and related 100 centimeters to a new unit, the meter (supporting work with the base ten system), they now relate 12 inches to a new unit, foot (supporting their work with arrays by recognizing that a new unit can be made with any value). They then use their inch rulers to measure and compare objects around the classroom (2.MD.1). Through practice, the foundational concept that the zero point on a ruler is the beginning of the total length and each number on the ruler indicates the number of length units from zero is reinforced.