So sad to learn of his death.
I was one of those young children taken to see him when he was under threat from the House Un-American Activities Committee. He must have sung children's songs, too, but what stuck with me were Woody Guthrie's "Union Maid" and Seeger's own "If I Had a Hammer." Perhaps they were children's songs back then.
The links are to early videos, before the great folk revival.
That up-lifted chin! An irreplaceable man.