What is Symmetry?
Symmetry is most easily defined as a shape being made up of exactly similar parts facing each other or when rotated around an axis.
Language
- reflection
- rotation
- transformation
Ask students to be on the lookout for places where they might encounter symmetry in their everyday life.
- Where in nature do you find things which are exactly the same on one side as on the other?
- Do you have any patterns in your home that might look the same when you rotate them?
Types of Symmetry
Many types of symmetry exist. The two most common are reflectional and rotational.
Reflection
- When a shape can be divided into two equal pieces by an imaginary line and each piece would be identical to the other when folded over.
- For instance, a circle could be divided in half in any direction and both halves would be the same.
- A square has four lines of symmetry, two diagonals and lines through the midpoints vertically and horizontally
Rotational
- If the shape can be partially turned without changing the overall shape, the shape has rotational symmetry.
- Examples of objects which have rotational symmetry are snowflakes or starfish with equally spaced legs.
Activities
Here are some great ways to encourage your students to have fun with symmetry:
- Cut various shapes – squares, rectangles, triangles, circles, etc. out of felt or construction paper. Allow students to design shapes. Ask them to create objects that demonstrate the different types of symmetry.
- Use rubber bands to identify the line of symmetry on three dimensional objects like cubes, tables, boxes, balls, etc.
- Use tracing paper, have students trace a letter of the alphabet and then fold the tracing paper in half to see if the letter has reflection symmetry or turn the paper to see if the letter has rotational symmetry.
- Use clay and cookie cutters to allow students to physically manipulate shapes to determine lines of symmetry
- Create a bulletin board of photos of symmetry found in nature, in homes, and at school.
