According to this story:
In the test, formally known as the National Assessment of Educational Progress in Arts, administrators at 260 public and private schools were asked how much time they devoted to art and music instruction, and 7,900 eighth-grade students were tested on art and music concepts, a small sample compared with other federal assessments. For example, in 2007, the department tested 700,000 students in reading and math, and 29,000 in history.
The Arts Report Card may be retrieved here, and the statement of Stuart Kerachsky, Acting Commissioner of the National Center for Education Statistics (NCES), may be downloaded here.
Source: Sam Dillon, “‘Mediocre’ Arts Skills for American Eighth-Graders,” New York Times, June 15, 2009.