This Problem Set is a part of the Lesson 8, Unit 1, Grade 3. In this lesson, students continue drawing and rotating arrays to demonstrate the commutative property of multiplication. This leads to the realization that each multiplication sentence is related to another, equivalent multiplication sentence (for example, students see that 2 groups of 8 and 8 groups of 2 have the same product) and that commutativity is a strategy for finding twice as many multiplication facts.