1.  Make as many polygons as you can using playing cards to tell you how long the sides have to be.  
Build a polygon
2.  Play tic-tac-toe while reviewing the traits of polygons.
Polygon Tic-tac-toe
3.  Teach symmetry with "negative" space.
Symmetry
4.  Symmetry worksheet
Draw the lines of symmetry
5.  Geometry PowerPoints
PowerPoints
