Practice with Polygons

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Students will be able to classify two-dimensional shapes using a hierarchy.

Big Idea

It's a square! No, it's a rhombus-rectangle-parallelogram-quadrilateral-polygon!


15 minutes

In this lesson students will be creating their own hierarchy of two-dimensional shapes that include quadrilaterals and triangles.  The previous lessons have used a one circle diagram and a Venn diagram to classify shapes.  Now, the students will be using a standard hierarchy to classify shapes. 

Although my students are somewhat familiar with the setup of a hierarchy, I feel it is necessary to open today’s lesson with a quick review.  I choose a topic that is relatively easy for students; Fruits and Vegetables.  I draw a quick diagram on the board and have students guide me in adding terms to our hierarchy.  I have included a sample of what I used in my classroom.  The idea here is that students are comfortable with creating and understanding a hierarchy. 



30 minutes

The last few lessons in this unit have led up to this point in which the students will use their knowledge of classifying shapes to create a hierarchy.  The hierarchy they will be creating today includes quadrilaterals and triangles.  The goal is that students are able to sort their polygons into a hierarchy based on the properties of two-dimensional shapes.  I have included a completed hierarchy.

Because this is a student led inquiry into creating the hierarchy, I don’t offer too much guidance on what they need to do.  I provide each group with a copy of the words needed for the hierarchy sort.  I have the students work in pairs and cut out their list of words they need to use for creating the hierarchy.  As students begin to work I circulate the room and check for understanding. 


15 minutes

To wrap up this lesson I play a quick game with students using their whiteboards.  This activity is called Can You Make It? and is taken from the second edition of Teaching Student Centered Mathematics by John Van de Walle.  The directions for the activity are to give the students challenges for shapes they have to create based on attributes.  More than one attribute may be given to the students at a time.  Here is a list of sample attributes taken from the book.

  • A shape with only one square corner and four sides
  • A shape with two square corners (or three, four, five, or six square corners)
  • A shape with one or two lines of symmetry
  • A shape with two pairs of parallel lines
  • A shape with two pairs of parallel lines and no right angles

I give the students an attribute or two and have them draw the shape on their whiteboards.  After allowing them a few minutes to think and draw, I have them share their solutions and support their thinking.