This Problem Set is a part of the Lesson 4, Unit 4, Grade 3. In this lesson, students count the square inch tiles on each side of a rectangle, and then measure the length of the sides with a ruler in order to notice that side length is equal to the number of tiles required to cover one side of the rectangle. From this experience, students can begin relating total area with multiplication of side lengths, and can skip count to find the area of rectangles.