I'm pretty sure the inchworm was a little lime-green guy; hope I'm not confusing it with the Muppet Show version because it's entirely possible that we still had B&W TV at the time, too.
In one or the other of the skits, there was a schoolhouse with little AM kids singing the refrain - I'm guessing that was the Muppet Show version?
Though the inchworm in that version was actually crawling on Danny Kaye, and I remember the lime-green guy on a fence, or piece of grass or something like that. I remember being impressed with the way it would lose its footing and reach it's little "head" up the way real inchworms do. I don't remember it being much more than a little flexible tube with feet on both ends, possibly slightly segmented.