This Problem Set is a part of the Lesson 6, Unit 3, Grade 6. Students use number lines that extend in both directions and use 0 and 1 to locate integers and rational numbers on the number line. Students know that the sign of a nonzero rational number is positive or negative, depending on whether the number is greater than zero (positive) or less than zero (negative), and use an appropriate scale when graphing rational numbers on the number line. Students know that the opposites of rational numbers are similar to the opposites of integers.