District School No. 3, also known as Putnam Schoolhouse, is a historic one-room school building located at Lyme in Jefferson County, New York. The schoolhouse consists of a 1+1⁄2-story, two-by-three-bay wood-frame main block constructed about 1875, and a 1-story, two-by-one-bay rear addition constructed about 1900. Also on the property is a double privy dating to about 1900.[2]