An unusual piece of contemporary composer Phillip Glass' history has appeared online in the form of three animations for Sesame Street.
From the Muppet Wiki it states:
In 1977, [Philip] Glass wrote a series of short vocal and instrumental pieces for Sesame Street. These include a series of animated films which employ geometric curves traced to various points on a circle to reveal other geometric shapes and colors. These works very closely resemble the "Dance" numbers written during the same time period as his Einstein on the Beach opera.And here are the clips:
Phillip Glass - Muppet Wiki
Phillip Glass Wiki
YouTube Clip1 Link
YouTube Clip2 Link
YouTube Clip3 Link
NOTE: Original image above from a photograph of Phillip Glass by Annie Liebowitz.