Review on Symmetry:

1) Line Symmetry -
http://www.linkslearning.org/Kids/1_Math/2_Illustrated_Lessons/4_Line_Symmetry/index.html

2) When you rotate a figure 360 degrees about a centre of rotation, the order of symmetry will be equivalent to the number of times you get the exact shape.

Rotational Symmetry - http://www.bbc.co.uk/schools/ks3bitesize/maths/shape_space/symmetry/revise4.shtml

Test yourself: http://www.bbc.co.uk/schools/gcsebitesize/maths/shapes/symmetryrev3.shtml
(complete the test bite and get 10 out of 10)

3) Plane Symmetry - http://e2bn.skoool.co.uk/content/keystage3/maths/pc/learningsteps/PLSLC/launch.html

For more interest, the following are some videos on how to make 3-D snowflakes; getting some sparks on bright ACE ideas?