Lesson plan

8. Areas of scale drawings relate by the square of the scale factor (FP)

teaches Common Core State Standards CCSS.Math.Content.7.G.A.1 http://corestandards.org/Math/Content/7/G/A/1
teaches Common Core State Standards CCSS.Math.Practice.MP8 http://corestandards.org/Math/Practice/MP8
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Lesson objective: Compute the area of scale figures by using the square of the scale factor and the original area.

This lesson helps to build "procedural skill" with computing areas of scale figures using the square of a scale factor. Rectangular arrays are used here because students can see how the area grows by the square of the scale factor as the dimensions grow by the scale factor.

Students engage in Mathematical Practice 8 (Look for and express regularity in repeated reasoning) as they build tables of areas of scale drawings to establish the relationship between the areas and the square of the scale factor.

Key vocabulary:

  • exponents
  • original figure
  • powers
  • proportional 
  • scale drawing
  • scale factor
  • square 

Special materials needed:

  • Optional: Pattern blocks, square tiles, or cubes for rectangular arrays.