Tuesday  February 7

Making Dissection Puzzles [more links] :

• Dissections (Junkyard)
• visit Dissection Animations
• visit The Puzzling World of Polyhedral Dissections by Stewart T. Coffin.
• Possible Portfolio follow up: Stein chapters 5 (Tiling) and 6( Tiling and Electricity)
  
• Another Reference for a possible project or portfolio entry:
  Equidecomposable polygons (translation from Portugese)

• Activity: Tile plane with playing cards.
• FAPP watch Video: Possible tiles and tilings.
• One Regular Convex Polygon.
• Two or more Regular Convex Polygons.
• Other Polygon Tilings.  
• Non polygonal tilings.

• One polygonal Tile: Quadrilateral Activity.
• An on-line tool for making tilings of the plane
• Regular and semiregular Tilings of the plane. Some explorations - classification.
  
• A tiling is a regular tiling if (i)it has a single tile shape that is a regular polygon and (ii) the vertices and edges of the tiles coincide (no overlapping edges)
• A tiling is a semi-regular tiling if (ii) each tile shape is a regular polygon, (ii) the vertices and edges of the tiles coincide (no overlapping edges) and (iii) every vertex has the same polygon types arranged around it.
  
• Wingeometry download! and demonstrate tesselations.
• Naming tilings (Math Forum)
• The numbers represent the number of sides in the poygons.
• The order indcates the order in which the poygons are arranged about a vertex.
  

• Semiregular Tilings: global results!
  Look at the results using wingeometry.
  
• Student lesson (Math Forum) a place for further explorations on-line.

• Symmetry Ideas
  
• Reflective symmetry: BI LATERAL SYMMETRY   
  
  T  C  O   0    I   A 
• Folding line: "axis of symmetry"
  

• The "flip."
  
• The "mirror."
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• R(P) = P'  : A Transformation. Before: P .... After : P'
• If P is on the line (axis), then R(P)=P. "P remains fixed by the reflection."
• If P is not on the axis, then the line PP' is perpendicular to the axis and if Q is the point of intersection of PP' with the axis then m(PQ) = m(p'Q).
  
  
  
• Definition: We say F has a reflective symmetry wrt a line l if  there is a reflection  R about the line l where  R(P)=P' is still an element of F for every P in F....i.e.. R (F) = F. l is called the axis of symmetry.
• Examples of reflective symmetry:
  Squares...  People
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• Rotational Symmetry.
• Center of rotation. "rotational pole" (usually O) and angle/direction of rotation.
  
• The "spin."
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• R(P) = P' : A transformation
• If O is the center then R(O) = O.
• If the angle is 360 then R(P) = P for all P.... called the identity transformation.
• If  the angle is between 0 and 360 then only the center remains fixed.
• For any point P the angle POP'  is the same.
• Examples of rotational symmetry.
  

•  Now... what about finding all the reflective and rotational symmetries of a single figure?
  

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• Symmetries of playing card.... classify the cards by having same symmetries.
  
  
  Notice symmetry of clubs, diamonds, hearts, spades