Reflection: Checks for Understanding Explore Perimeter and Area of Composite Shapes - Section 2: Guided Practice + Independent Problem Solving


I noticed some simple counting errors on some of the shapes, especially when finding the perimeter of the shapes.  Students would often count a "rail" twice or skip some rails altogether.  I noticed that students who counted the rails correctly had some method for keeping track of what had been counted.  For the perimeter, they often used tick marks and for the area they often used dots.  I presented these on the document camera for students to see. 

It seems like a very basic thing to have to correct, but it is important.  The point in the lessons is for students to see how area and perimeter interact and that shapes with the same area do not necessarily have the same perimeter (and vice versa).


  Careful Counting
  Checks for Understanding: Careful Counting
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Explore Perimeter and Area of Composite Shapes

Unit 6: Geometry
Lesson 1 of 37

Objective: Students will be able to explore the differences between area and perimeter using models

Big Idea: Students further their understanding of area and perimeter by first considering a design for a bumper car ride.

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25 teachers like this lesson
Math, areas, circumference (Determining Measurements), Geometry, area, Perim, composite shapes, circles, perimeter, Diameter, pi, 7th grade
  36 minutes
rails tiles
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