ACTIVITY 1

Butterflies--Lines of Symmetry

Teaching Ojectives:

1. Students will learn through observation what the term bilateral symmetry means.
2. Students will observe that not all butterflies are symmetrical in the same ways.
3. Students will learn through a discovery approach that there is more than one way to approach scientific investigation.
4. Students will learn to work together to solve a problem
5. Students will learn to take careful notes during their investigation of a problem.

Materials Needed:

• School Day pictures of students' faces
• Butterflies (one for each group of students working on the activity); have the students collect them or order from Biological Supply Houses
• Small unframed rectangular mirrors (one for each group)
  
• Worksheets divided into six blocks; outline of a butterfly in each block (optional)
• Butterfly Symmetry Worksheet

Procedure:

Discuss the concept of bilateral symmetry with the class. Bring examples of things that are bilaterally symmetrical (a glass, a vase with handles on each side, an apple cut in half) and things that are not (a mug, a stapler, a computer keyboard).

Ask the students if there are things that the students recognize as being bilaterally symmetrical. Lead the discussion to animals (human beings included) and insects. How are they bilaterally symmetrical?

Use a picture of the full view of someone's face and show how it is bilaterally symmetrical. Use a picture that will stand out in the students' minds--a clown or the teacher's face decorated with a mustache, funny glasses, and a nose! Have the students look for symmetry in their school-day pictures.

Divide the students into groups of two and give each group a butterfly, a mirror, and a worksheet.

Tell the students to check for symmetry by holding the mirror perpendicular to the butterfly's body. The students should look in the mirror first and then look on the opposite side of the butterfly. If what appears in the mirror is the same as what the students sees when looking directly at the opposite side of the butterfly, then bilateral symmetry exists. Let the students consider the number of directions that symmetry could be checked.

Have the students diagram each way that they checked for symmetry in one of the blocks on the worksheet. If they are really young students, teachers might want to draw the butterfly outlines in the blocks prior to making copies of the worksheet; older students can draw their own. Point out that the students should record all of their observations, even those that did not show bilateral symmetry.

Have the students indicate in individual blocks whether bilateral symmetry exists in each direction or not.

Class Discussion:

After the students have made their scientific observations, discuss the following questions:

What are the different ways for which symmetry could be checked?

1. Were any of the butterflies symmetrical in more than one direction?
2. What was the greatest number of ways that any one butterfly was bilaterally symmetrical?
3. Were any of the butterflies not symmetrical at all?

Supplemental Activities:

Pair each student with another. Using a large piece of construction paper, have one student draw one side of a face. Then have the student's partner draw the other side of the face, making it as bilaterally symmetrical as possible.

Demonstrate cutting out an object that is bilaterally symmetrical by folding a piece of paper in half and using the fold line as the center of the object. Things such as hearts, pumpkins, and leaves can be cut easily this way. Encourage the students to design and cut out more complex designs.