Intro #2 Composite Area Finding Area by Decomposing and Rearranging

This is an adaptation of OUR Grade 6 lesson 1-2. Student Facing Goals I can explain how to find the area of a figure that is composed of other shapes. I know how to find the area of a figure by decomposing it and rearranging the parts. I know what it means for two figures to have the same area. Lesson Narrative The area of two-dimensional figures can be determined in multiple ways. We can compose a figure using smaller pieces with known areas. We can decompose a figure into shapes whose areas we can determine and add the areas of those shapes. We can also decompose it and rearrange the pieces into a different but familiar shape so that its area can be found. The two key principles in this lesson are: Figures that match up exactly have equal areas. If two figures can be placed one on top of the other such that they match up exactly, then they have the same area. A figure can be decomposed and its pieces rearranged without changing its area. The sum of the areas of the pieces is equal to the area of the original figure. Likewise, if a figure is composed of non-overlapping pieces, its area is equal to the sum of the areas of the pieces. In other words, area is additive.

By Todd Steinhauer