This Problem Set is a part of the Lesson 13, Unit 1, Grade 3. In this lesson, students draw tape diagrams to represent division word problems and determine whether the size of each group or the number of groups are unknown. For example, by representing the situation, "Three students equally share a pack of 12 pencils" as a tape diagram, students are able to see that the size of each group is unknown. They also contrast two tape diagrams that represent related division facts (e.g.