Hint: This is the inside of an object that you have probably only seen from the outside.
Shown above are examples of various notation systems for what? (Clarification: I am looking for one answer, not seven.)
These are all forms of dance notation. If you look closely, one of them has a little dancer in it:
How would you even begin to represent a dance on paper? It's inherently hard—maybe that's why so many attempts at a notation system have been invented. For more about this fascinating subject, check out this article: How to Write a Dance.
Congratulations to solvers Leo S., Maddy, Jessica, and Dr. Yetman!