From the creators of ABC's award-winning Schoolhouse Rock comes The Metric Marvels, a group of educational "superheroes" who debuted on NBC in 1978. Unfortunately, the Marvels (Wonder Gram, Meter Man, Liter Leader, & Super Celsius) didn't last very long, as only 7 shorts were produced. None of those shorts are available on YouTube, and all I can find is this black & white intro:
Schoolhouse Rock regulars Lynn Ahrens & Bob Dorough were joined by toon icon Paul Winchell in voicing the four Marvels. The idea was that, in the late 70's, there was a movement to introduce the Metric system to the US. It didn't quite take, as we're still using more traditional means. A nice idea, but it just wasn't meant to be.