This Problem Set is a part of the Lesson 18, Unit 1, Grade 1. In this lesson, students use pictorial representations (pictures and 5-groups) to evaluate whether equations are true or false. For example, they examine the false equation 4 + 2 = 5 + 3 and count on to determine that the totals on each side of the equation are not the same. Then they devise ways to change one side of the equation to make it true.