Lesson Plan : Symmetry and the use of Geoboards

Teacher Name:
 Ms. Bair
 Grade 3

 The students will use mirrors to explore lines of symmetry. The students will use geoboards to create shapes and then show their line(s) of symmetry. The students will create a Valentine's Day card using symmetry.
 The students will be able to show the line(s) of symmetry when given or asked to draw a shape or object (like a butterfly) with 100% accuracy. SOL(s): Geometry 3.20 The student, given appropriate drawings or models, will identify and describe congruent and symmetrical, two-dimensional (plane) figures, using tracing procedures. Patterns, Functions, and Algebra 3.24 The student will recognize and describe a variety of patterns formed using concrete objects, numbers, tables, and pictures, and extend the pattern, using the same or different forms (concrete objects, numbers, tables, and pictures).
 Mirrors Shape Cutouts Geoboards with rubber bands Geoboard dot paper Symmetry worksheet Markers Scissors Glue sticks Construction paper in various colors (may need overhead and/or computer projection for interactive geoboard @ http://standards.nctm.org/document/eexamples/chap4/4.2/index.htm)
 Introduce symmetry by getting the students to help explain it. If now prior knowledge, use some examples from nature like butterflies, seashells, starfish, animal bodies, flowers, leaves, etc all are symmetrical meaning that if you were to cut them in half (and sometimes more) you would have equal sides or balanced porportions. Can you all think of some other examples? Let's do some shapes together.
 Draw a triangle on the board. Ask for the students to show where the triangle could be cut in half to show equal sides. (there are three) Next do a rectangle.
 Pass out the shape cutouts and mirrors and ask the students to use the mirrors like the line of symmetry to see if the mirror reflects back an equal proportion from the first half. Let them explore and then ask them to show where the lines of symmetry where on each of the shapes (have them up on an overhead or drawn on the board)
 To make this a little harder, ask students to create their own half of an object on the geoboard and give it to a partner to figure out and vice versa. To make this lesson a little easier, use the basic shapes like triangles, rectangles, circles, squares, and parallellograms only. Maybe have these students use pattern blocks and yarn to show the lines of symmetry.
Checking For Understanding:
 Handout the Creating Lines of Symmetry Worksheet and have the students use pencils or different colored markers to show the lines of symmetry. After they have completed that, show them the pre-made Valentine's Day card and explain to them how they can use symmetry with folding shapes and cutting to create homemade cards. Have them create a Valentine's Day card for someone in their family or maybe for the teacher :)
 Review symmetry by asking the students to define it for you. Give a shape like a square and ask individual students to put up one of the lines of symmetry. Then, give a half completed shape and ask someone to come up and finish it. Do this 2-3 times.
 Look at geoboard dot paper assignment and the lines of symmetry worksheet assignment for each student to gauge their understanding. Also, look at the Valentine's Day cards and make note of those who seem to not be able to create symmetrical shapes using paper for that assignment.
Teacher Reflections:
  * Which students demonstrated an understanding of the objectives of this lesson? What were the indicators that they did understand the objectives? * Which students had difficulty with the activities in this lesson? What additional instruction do they need? * What strategies were most effective in assessing each studentís learning in this lesson? * How else can I accommodate students who moved quickly through each aspect of the lesson? Is it important to note the extensions that worked well?

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