I advise both of you to use the art curriculum framework documents from
the TEA Center for Educational Development in the Fine Arts (CEDFA) to
support your arguements. The website is:
Click on "Art" then "Curriculum Framework" it will download to your
computer. Look under "Special Considerations" and "Special Education"
and also under "Campus and District-Level Considerations"
The framework is an official Texas Education Agency document so it carries
a lot of influence with Administrators.
I hope they get your class size down to the recommended number of
students soon.