Have a look at this powerful Arts Education advocacy document coming out of the United States. An interesting read with great resources on why arts in education make students successful in school, work and life.
The Arts Education Partnership, who wrote the report has a great website and links to all kinds of resources.
Here is their mission:
The Arts Education Partnership is dedicated to securing a high-quality arts education for every young person in America.
In-school and out-of-school—each and every day—all children need the opportunity
…to learn about and
the arts in all forms, including dance, music, theatre, and visual arts.
And, they have a research website dedicated to research about arts education in schools: