median
don steward
mathematics teaching 10 ~ 16

Monday, 23 July 2012

frieze patterns












these Maori designs are good examples of frieze or strip patterns

the topic seems an interesting way of following up work on symmetry

Heather McLeay (Bangor University, North Wales)  has championed including a study of frieze (strip) patterns; her photographs of the seven different types are here

a frieze is an infinite strip of a repeating pattern, 1D only
you can establish that there can only be 7 types of these

a glide reflection is where you reflect and then move the shape along a bit (like footsteps in the sand)

the Illuminations program on this topic allows generating shapes to be modified (by dragging) which might help understanding

there are several notations for classifying the 7 strip patterns and, once appreciated, students can be asked to analyse the symmetries and so recognise the types in various examples

the symmetries are of an infinite strip rather than just a 'window' section

some symmetries take precedence in the notations

this notation is due to the IUC (crystallography based)

a youtube clip, geese















John Conway devised his own notation, based images of the symmetries as various 'steps' (students can act these out)







an identification key
which of the 7 types are which?





















for a (later) review








the 17 possible wallpaper patterns
a wallpaper key

 

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