GEOMETRY LESSON: 

          Sorting Quadrilaterals: Defining Parallelograms

                     Click [HERE]for a follow-up lesson

Author:  Dr. Mavis Kelley

  TEACHER'S NOTE: This is one of my favorite lessons (I must admit that I
  have many favorites in math).

             Sorting Quadrilaterals:  Defining Parallelograms

  Materials: Sets of cut out quadrilaterals for each group of students
  and one for the teacher.  (I make each set a different color so that 
  it's easy to keep the sets complete. Then I store them in a small manila
  envelope.) Math logs;

  Concepts: Geometry (Quadrilaterals, Parallelograms, and others)
  Introducing parallelograms

  Goal: Students will write their own definition of a parallelogram based
  on the data gathered during the activity.

Procedure:

        1) Give each group of students a set of quadrilaterals and keep 
        one set for yourself.

        2) Draw two circles on the board and label one "No" and one "Yes".

        3) Your goal as a class is to sort the quadrilaterals in the two
        circles based on the concept of parallelogram.  Eventually, all the
        quadrilaterals that are parallelograms are taped in the "yes" 
        circle and the non-parallelograms in the "no" circle.
        
        4) To begin, hold up a parallelogram (without naming it), show it 
        to the students, and direct them to find their matching polygon.  
        Once they have found it, attach the shape in the "yes" circle.

        5) I don't tell the students the concept or name (parallelogram) 
        yet.This should come from the activity.

        6) Select a non-parallelogram and hold it up. Once students have
        found their matching shape, attach yours inside the "no" circle.

        7) From this point, I ask each cooperative group to agree on a
        quadrilateral. I call on one group at a time to hold theirs up.  
        Everyone finds their matching shape, and I ask for predictions as 
        to where I'll attach it.

        Repeat this process until all quadrilaterals are inside one of
        the circles.

        8) The next phase of the activity involves students writing
        descriptions in their logs. I ask them to make a "T-Chart."  
        On one side they write what all the shapes in the "yes" circle have 
        in common.  In the other side, they write what is different about 
        the shapes in the "no" circle (different from the "yes" shapes).

        9) After students have discussed the similarities and differences, 
        we make a class chart.

        10) Once this process is complete, I ask the students if anyone 
        knows the name for the polygons in the "yes" circle. 
        [PARALLELOGRAM] 

        I then ask students to write their own definition for a 
        parallelogram in their logs.

        11) Students share their definitions in class. After several
        definitions, I might ask questions such as, "Who has written a  
        definition with information in it that has not yet been shared?"  
        "Who can add to the definitions we have heard so far?"
        At times, I construct a shape that fits their definition, yet does
        not fit the definition of a parallelogram.  This way, they have an
        opportunity to self-correct.  I then ask, 

        "Is this shape a parallelogram?  Explain your thinking."