Discovering Area Relationships
Students discover the area formulas for triangles, parallelograms, and trapezoids. They apply formulas to find areas of irregular shapes.
This can be done as a whole class or with partners. Project (or provide copies) of the "Cork Costs" graphic. Ask students: What do you notice? What do you wonder?
Students develop the area of triangles formula using the area of rectangles and by comparing triangles with equal bases and heights.
Students use prior knowledge of the area formula for rectangles and triangles to discover the formula for the area of parallelograms.
Students explore several strategies for calculating the area of a trapezoid while discovering the area formula for trapezoids.
Students will estimate the area of irregular shapes and use a process of decomposition to calculate the areas of irregular polygons.
Error- the essential questions and connecting standards on the right hand side of the webpage for discovering area is for a different ARC -
Some HOOK suggestions:a Which Ones Doesn't Belong activity; "square peg in a round hole" clip from Apollo 13 movie would need an intro to the Apollo 13 story and that "round" is not part of this lesson;
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How can you build the longest bungee cord for Barbie that keeps her safe?
CCSS, Content Standards to Domain Level
CCSS, Standards for Mathematical Practices
Effective PtA, highlighted Effective Teaching Practice and/or Guiding Principle CCSS
Original author: Samuel E. Zordak
Illuminations lesson: Barbie Bungee
CRDT team: Luke Wilcox, Deidra Baker, Jerel Welker, Michelle Greene and Lindsey Gallas