18.4 Symmetry

We will discuss two kinds of symmetry:

1. line symmetry: reflection across a line of symmetry

- the image below has line symmetry, this is shown with the dotted lines

2. rotational symmetry: turning around a center point (point of rotation) and lining up again

-the flowers above also have rotational symmetry because you could turn them and have them line up again.

Check out these links from mathisfun.com for line symmetry and rotational symmetry

• Check out this illustration from innovations learning that shows lines of symmetry in shapes
• Here is game from innovations learning that will check your understanding of lines of symmetry form

18.2 Tessellations (p.397-399)

A tessellation is a design of repeating shapes that fit together without gaps or overlaps.

Shapes that tessellate easily include:

• triangles (three sided)
• quadrilaterals (four sided)
• parallelograms (opposite sides parallel - and congruent)

This link from DIY Tessellations is very helpful for helping you think about how to make your own tessellation.

M. C. Escher is likely the best known artist who used tessellations. Check out this link with some of his tessellations:

Here is a link of "wallpaper patterns" that Escher used as inspiration

18.1 Transformations

Check out these links for more exploration with transformation:

• This link uses shapes to model what we did during story time.
• Link from UTC.edu used during "story time" with examples of transformations.
• http://www.bbc.co.uk/schools/ks3bitesize/maths/shape_space/transformations1/revise1.shtml