The above photograph depicts the Johnsville (MD) Public School class of 1917. The school building, located in Johnsville, MD at what is now 10808 Green Valley Road, Union Bridge, MD, was built in 1903 and is now used as a residence. A 1991 image of the school and other details about Johnstown were found in the Architectural Survey File produced by the Maryland Historical Trust for its Inventory of Historic Properties.
The principle of the school, on the far left holding his hat in his hands, was Daniel Oliver Metz (1860-1949). I was able to confirm this is an image of Metz by comparing it with images of him posted by genealogists on Ancestry.com. Metz replaced George Klein Sappington (1855-1916) as principle of the school in 1891 with Emma Jane Sayler (1868-1929) as his assistant. I could not confirm that the woman in sunglasses on the far right in the image is Sayler.
Metz was the son of Nicholas Metz (1833-1904) and Mary Susan Albaugh (1837-1918). He married Olivia E. Eaves (1860-1941) in 1887, the daughter of Ephraim Eves (sic) (1835-1904) and Mary Jane Filler (1834-1920). All were Natives of Maryland. They had two children who lived to adulthood, Charles Daniel Metz (1895-1973) and Hilda Eaves Metz Bohn (1900-1960). Metz taught in Frederick County public schools for 33 years and was active in the Beaver Dam Church of the Brethren (Dunkard Brethren) for over 50 years as an elder, minister, and Sunday School teacher.
Emma Jane Sayler (variant Saylor) was the daughter of Solomon Sayler, Jr. (1824-1903) and Harriet Albaugh (1829-1905). She married James Daniel Leakins (1868-1941) in 1898 and they had a daughter, Lettie Pauline Leakins (1900-1965) who married Hall McCauley Martin in 1919. Given Metz’s longevity as principle at the Johnsville School it doesn’t seem unreasonable that Sayler was still the assistant in 1917 and the woman in this image looks age appropriate, but the only mention of Sayler as a teacher was in 1891 when she was appointed; all available Census records inform that she had no occupation.