In previous lessons, students have learned to use the standard algorithm to multiply whole numbers including a three-digit number by a two-digit number. The purpose of this lesson is to apply those techniques to a situation involving areas related to the Great Pacific Garbage Patch. The measurements are given in kilometers, so in the first activity, students review the length of a kilometer. Then they calculate the area of different U.S. states to get a sense of the size of the Great Pacific Garbage Patch. One of the calculations is a product of 2 three-digit numbers. After this brief interlude, solving problems about area, students return to volume for the final two lessons. The area calculations for the U.S. states showed the importance of estimation, since finding the exact products requires careful calculations, whereas a quick estimate shows that the area of New Mexico is less than the area of the Great Pacific Garbage Patch. This estimation builds on students’ learning from the previous activity, and then next two lessons combine estimation, volume, and trash.

In what ways did students extend and apply their understanding of multiplication and area throughout the lesson?