Thursday, 2 February 2012

Shape. Symmetry

  1. Why learn about symmetry? 
  2. What do you notice about shapes or designs that have symmetry?
  3. Does it make a difference if the line of symmetry is vertical or horizontal? Why or why not?
  4. Locate two objects in the classroom: one that has symmetry and one that has not. Explain the differences.
-->   Symmetry is perhaps most familiar as an artistic concept than a math concept. Designs are said to be symmetric if they exhibit specific kinds of balance, repetition an harmony.

Think of the form of a butterfly; its right and left halves mirror each other. If you knew what the right half of a butterfly looked like, you could construct the left half by reflecting the right half over a line that divides the butterfly.
A line of symmetry divives a figure into two halves that are the mirror images of each other.
See the difference between both trees.

Types of symmetry_____________________________________________

Plane symmetry involves moving all points around the plane so that their positions relative to each other remain the same, although their absolute positions may change. Symmetries preserve distnces, angles, sizes, and shapes.
  • Rotation by 90 degrees about a fixed point is an example of a plane symmetry.
  • Reflection of a figure is when seen in a mirrow or atransparent surface. Another way to make a reflection is to fold a piece of paper and trace the figure onto the other side of the fold.
  • Traslation it is like moving the shape over and it is exactly the same the whole time. It just repeats and repeats.

1. Reflexion symmetry__________________________________________
  Miror symmetry is present whenever an object or design can be broken down into two parts, one of which is the reflection of the other.

Reflection symmetry is quite common in nature and art.


2. Rotational symmetry_______________________________________
      An object that has rotational symmetry will appear unchanged if rotated through an angle. A circle can be rotated any amount and still look like a circle, but most objects can be rotated only by some specific amount, depending on the design.

To know more about symmetry click here. If you want to play chek this: Game. Try it!

  1. Make strings of paper dolls or snowflakes by cuttinh a strip of folded paper to show an easy way of creating symmetry. There is a program that allows you to create your own snowflake.
  2. Answer the questions in your woorksheet after watching this Power Point Presentation: Symmetry/yrtemmyS
  3. Exercises with axial symmetry.
  4. Exercices with radial symmetry.
  5. Working with your name

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