This primary source comes from the Records of the War Department General and Special Staffs.
Full Citation: Children of the Irving-Jefferson School of Plainfield, New Jersey, Learning to Knit. Knitting in school room, 1st grade; 1917 - 1918; Girls' Activities - Miscellaneous; American Unofficial Collection of World War I Photographs, 1917 - 1918; Records of the War Department General and Special Staffs, Record Group 165; National Archives at College Park, College Park, MD. [Online Version, https://www.docsteach.org/documents/document/children-irving-jefferson-school-plainfield-new-jersey-learning-to-knit-knitting, May 14, 2024]