Lesson plan

# Solve for the area of a composite figure by decomposing it into rectangles, triangles, and other shapes

teaches Common Core State Standards MP6 http://corestandards.org/Math/Practice/MP6
teaches Common Core State Standards MP4 http://corestandards.org/Math/Practice/MP4
teaches Common Core State Standards MP1 http://corestandards.org/Math/Practice/MP1
teaches Common Core State Standards 6.G.A.1 http://corestandards.org/Math/Content/6/G/A/1

# Solve for the area of a composite figure by decomposing it into rectangles, triangles, and other shapes

Big Ideas: Area is additive. The total area of a figure can be found by adding together the areas of the figures within the shape. Decomposing a composite figure into rectangles, triangles, and other shapes is one way to find the total area of the composite figure. This lesson builds on students’ work with solving for the areas of composite figures. This task provides students with an opportunity to compose and decompose different composite figures using rectangles, triangles, and other shapes. By composing and decomposing different shapes, students will realize that area is additive and that the area of a figure is the sum of all of the areas of the shapes within the figure. The mathematical concepts in this lesson build toward students’ future work with surface area and describing the 2-D figures that result from the slicing of 3-D figures in grades 6-8. Vocabulary: area, decompose, compose, composite figure, rectangle, triangle Special Materials: Grid Paper Scissors Tape or Glue Supplementary Handout