Symmetry anchor chart- a great idea for when kids start learning about symmetry to use as a reference sheet. I would have the class come up with symmetrical objects to add to it.
Winter Crafts for Kids: Creating Symmetrical Snowflakes~ Buggy and Buddy: Snowflake Bentely
pattern block snowflakes on circles - really cute idea, but very labor intensive to cut out enough pieces for your class. another idea would be to have students trace the pattern block pieces to make snowflakes