This photo is from the McCoy family collection. It shows graduates of a plumbing school in Newburgh, NY in 1902, and one of the graduates is John P. McCoy, who was a plumber in Fond du Lac. Sure looks like the back wall was their final exam!
Members of this group, as listed in a sign in the picture are: J P McCoy, Fond du Lac, WI; W Palmer, Port Huron, Mich; P J McMonagle, Port Huron, Mich; W M Spencer, East Jordan, Mich; Clarence E Lewis, Fall River, Mass; Harry R Turby, Wilkesbarre, Penn; C G Fuller, Rochester, NY; Leo Ladd, Hoosick Falls, NY; J M Krakauer, Chihuahua, Mexico; Alex List, New York City. J P McCoy is in the group on the left, standing next to the water heater.