Lessons 138-170 Unit 5 covers addition and subtraction 16's-18's. The workbooks have continuous review built into the lessons. They include reading problems, speed drills, and pounds and ounces are introduced. The teacher's manual is important for using the course effectively. It give directions on how to use the workbooks, oral drill, and, of course, the answers. That is a time saver. They are reusable.
