Classifying Polygons

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Students will be able to classify two-dimensional using more than one attribute.

Big Idea

Venn Diagram meets 2-D shapes!


15 minutes

In this lesson students will be classifying polygons based on more than one attribute using a Venn diagram.

To begin the lesson I bring students to the computer lab for interactive review.  I have them go on the Illuminations website to the Shape Sorter interactive.  This resource allows students to practice the type of classifying they learned in the previous lesson which was sorting based on one attribute.  The interactive is pretty straight forward so I let the students begin without much instruction. 

As the students are working in the Shape Sorter, I circulate the computer lab and check for understanding.  I ask students to explain their thinking as to how they determined which shapes fit the attribute. 


30 minutes

The main portion of this lesson is an extension of the previous lesson in which students we sorting polygons into one circle.  In this lesson students will be challenged in their understanding of classifying shapes by requiring them to classify shapes based on two attributes. 

I provide students with a copy of the Venn diagram and the polygons they used in the previous lesson.  I also provide them a copy of the sorting cords and have the students cut the shapes out.

To begin the activity I briefly explain the directions to the students.  They will be working in groups again while using the Venn diagram, polygons, and sorting cards.  The group will draw two cards from the sorting pile and place them above the Venn diagram circles.  They then need to work as a group to discuss which shapes belong within the diagram.  There may be some shapes that do not fit within the diagram. 

I have them raise their hand when they are finished with the first sort and I check for understanding and accuracy before allowing them to move on to drawing two more sorting cards.


15 minutes

To wrap up this lesson I give the students an opportunity to show their understanding of classifying shapes by defending their thinking.  I display a Venn diagram that has already by sorted but it contains two mistakes.  One side of the diagram contains shapes that have opposite sides parallel while the other side has at least one obtuse angle. 

The two mistakes are as follows; the square should be on the left side of the venn diagram and the hexagon should be in the middle of the diagram. 

I have students view the picture on their own for a few minutes then have them discuss with their neighbor.  After allowing the students about five minutes of discussion I have them record their thoughts in their math journal.  This is just a quick write and will not be collected.  It is just a chance for students to verbalize then write their thinking. 

Finally, I have the students share their written responses and address any misconceptions during a class discussion.