Description: Students work with the standard algorithm for subtraction in Topic E. As in Topic D, they use two- and three-digit metric measurements and intervals of minutes within 1 hour to subtract. The sequence of complexity that builds from Lessons 18-20 mirrors the progression used for teaching addition. In Lesson 18, students begin by decomposing once to subtract, modeling their work on the place value chart. Lesson 19 adds the complexity of decomposing twice to subtract. Minuends may include numbers that contain zeros in the tens and ones places. Lesson 20 consolidates the learning from the two prior lessons by engaging students in problem solving with measurements using the subtraction algorithm.*Teacher Advisor is 100% free.