Duncan attended Tamalpais High School, known as Tam High, in Mill Valley, California. He contributed to two of The Pia yearbooks, in 1926 and 1927. The earlier pieces in this gallery were no doubt influenced by Howard Pyle's books on the adventures of King Arthur, which Duncan would have seen growing up. Duncan's pieces from 1927 appear rushed in comparison to the earlier work, but in fairness, he was much more active in school during this period. This was also the year Duncan left school to begin working for The Sausalito News, at the age of 17.