When we submitted our package, we were advised to not include examples of school work, but outside of school examples. We included:
photo montage of a "book" she wrote and illustrated in first grade
photo/scan of some math work she had done for fun
photo/scan of a Venn diagram she had done for fun of the similar/dissimilar characteristics of types of cats
Other people I know included:
photos of Lego structures
photos of art work
sample of music the student could play and a photo
We also got a letter of recommendation from a music teacher, and we included two certificates she had earned for participation in outside of school events.
Many people I know include nothing beyond the base package, but I would not recommend that.
