Symmetry in Shapes and Everyday Objects

Designed by:  Ashley Norton, Rosewood Elementary

Grade Level:  Fourth      Subject:  Geometry

1) Curriculum Objective:  Identify and/or draw lines of symmetry in a given object or representation. (4GS3-1)

2) Overview: This activity will provide students with the opportunity to discover and find lines of symmetry for shapes and everyday objects.  The teacher will provide students with a butterfly outline and have students find a line of symmetry for the pattern.  Students will also discover that some objects have more than one line of symmetry.  Using a sheet of construction paper, students will fold the paper  to discover that the paper has two lines of symmetry.  Student pairs will be given pattern blocks, leaves, paper, and a Cheese-It cracker to discover and draw lines of symmetry. Students will go on a "Detective Symmetry Search" to discover everyday objects that have at least one line of symmetry.  Bonus points will be awarded to student pairs who find and identify objects that have more than one line of symmetry.

3) Focus Question:  How can you identify and draw lines of symmetry in everyday objects and shapes?

4) Resources:

Butterfly pattern

Piece of blank construction paper for each student and the teacher

One pair of scissors (Option-scissors for the class)

Overhead Projector

Overhead Pattern Blocks (square, triangle, diamond, hexagon, trapezoid) **Pattern block sheet is attached at the bottom of lesson if you do not have access to these materials.**

Box of  toothpicks

Set of Pattern Blocks for each student group (square, triangle, diamond, hexagon, trapezoid)  **Pattern block sheet attached if you do not have access to these materials.**

Leaf from a tree or bush for each student group

One piece of copier paper for each group

Square cracker (Cheese-It)

Copies of culminating assessment for each student

Pencils

Math notebooks

5) Culminating Assessment:

The students will each be given a copy of  the culminating assessment.  The teacher should go over this assessment and make sure the students understand the assignment and the expectations.  Students will receive five points for each correct response and 2 points for incomplete responses.  For example, if an object has 2 lines of symmetry and the student only identifies one line of symmetry, the student will receive 2 points.  If the student does not respond to an item or if the response is incorrect, no points will be received. Students will receive two bonus points for each extra line of symmetry they show in the items they choose.

Total Number of Points: ___________________

Comments:

6) Instructional Activities:

This lesson is expected to take two one hour class periods.

Lesson 1:
The teacher should hand out the culminating assessment and explain it to the students.  The teacher will introduce the concept of symmetry by holding up a picture of a butterfly (attached at the end of this lesson) and asking, "Does anyone see a way that I can cut this picture in half and have each side exactly the same?"  Provide the student who responds with a copy of the butterfly and a pair of scissors.  Have the student cut the picture in half according to what he thinks is the correct response.  Ask the question again and see if there are any other responses.  Have extra copies of the butterfly and the pair of scissors available for students to try out their responses.  Show the students the correct response (the butterfly is divided vertically in half) and demonstrate how each side is exactly the same.  (Hold the picture up in the air and turn one half over and place it on top of the other side to show that they are exactly the same.)  Explain that the place where the picture was divided is called a line of symmetry.  The teacher should begin a discussion with students about other objects in nature that have lines of symmetry (animals, insects, some plants. humans).

Next, students will learn that some objects have more than one line of symmetry.  Hold up a sheet of blank construction paper.  Ask for volunteers to find a line of symmetry.  Give each student a piece of blank construction paper to allow them to explore by folding the paper.  The students may work together if desired.  Student volunteers should demonstrate to the class how the paper has two lines on symmetry, one going vertically and one going horizontally. Make sure that the students understand that the rectangle cannot be divided diagonally because it is not divided evenly.  The students can fold the paper diagonally to see this for themselves. (Option- The teacher may want the students to cut the paper along the lines of symmetry with scissors.)  Ask if there are any questions and make sure all of the students are understanding the lesson so far. Have the students write the following definition in their Math notebooks:  A line of symmetry divides an object into two equal parts.  Some objects have more than one line of symmetry.

To further illustrate this definition, divide the students into pairs according to high/low ability.  Give each pair a set of pattern blocks.  (If you do not have access to pattern blocks, you may make copies of the attached pattern block sheet and give it to the students.)You will need your overhead projector and overhead pattern blocks. (If you do not have overhead pattern blocks, make a copy of  the attached pattern block sheet onto a transparency. You may want to color each piece a different color to make them show up better on the overhead projector.)  Pass out a small handful of toothpicks to each student pair.  The students will use the toothpicks to show lines of symmetry.  The teacher will put the square pattern block on the overhead projector  and the students will put the square pattern block on their desks.  The teacher will explain that the toothpicks are to be used to find the lines of symmetry.  Students should find one line of symmetry for the class and the teacher should demonstrate on the overhead how the toothpicks are to be placed on top of the square to represent the line of symmetry that was found. The teacher should allow several minutes for the groups to explore the square and find as many lines of symmetry as possible, placing the toothpicks across the square to show the lines of symmetry. (Option-Students having a difficult time with this concept may want to trace the square into their math notebooks, cut it out, and fold it to find the lines of symmetry.)  The students should discover that there are four lines of symmetry for the square. The teacher should be walking around the room and assisting groups as needed and to check for accuracy.  This information should be recorded on the culminating assessment sheet provided by the teacher at the beginning of the lesson.  The students and teacher should follow this same pattern for the triangle.

Lesson 2

The teacher should review from Lesson One to make sure all students understand the concepts and the teacher's expectations.  The teacher should pass out the remaining items from the culminating assessment sheet (pattern blocks, toothpicks, leaves, copier paper, and cheese crackers).  The students should then be instructed that they are going on a "Symmetry Detective Search" around the school to find two objects with lines of symmetry to use for their culminating assessment.  Each pair should find two items with at least one line of symmetry and bring them back to class.  The teacher should remind students that they will receive two bonus points for each line of symmetry in addition to the first one in their objects. Once the students have found their items and returned to class, the students should work in pairs to complete their culminating assessment activity using the objects they have collected and the remaining items from their activity sheet.  The teacher should assist student groups having difficulty as needed.  Students who finish early may assist other student groups by checking and discussing their work.  The teacher should collect the culminating assessment activities.