Finding the area of irregular figures
http://illuminations.nctm.org/LessonDetail.aspx?ID=L583
A lesson plan for grades 6–8 Mathematics
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Students will estimate the areas of highly irregular shapes and will use a process of decomposition to calculate the areas of irregular polygons. Illuminations provides activity sheets, a link to the patch tool, and detailed instructions for completing the lesson.
Students will:
- Estimate the area of irregular shapes.
- Decompose irregular polygons into squares, rectangles, triangles, and other familiar shapes.
- Determine the area of an irregular polygon by summing the areas of its composite shapes.
North Carolina Curriculum Alignment
Mathematics (2004)
Grade 6
- Goal 3: Geometry -The learner will understand and use properties and relationships of geometric figures in the coordinate plane.
- Objective 3.04: Solve problems involving geometric figures in the coordinate plane.
Grade 7
- Goal 3: Geometry - The learner will understand and use properties and relationships in geometry.
- Objective 3.02: Identify, define, and describe similar and congruent polygons with respect to angle measures, length of sides, and proportionality of sides.
