170402-N-PO203-295 NATIONAL HARBOR, Md. (April 2, 2017) Rear Adm. David Hahn, chief of naval research, watches as Midshipman 3rd Class Mitchell Winkie conducts an experiment during the 2017 Naval Stem Exposition, co-sponsored by the Navy League of the United States and the Office of Naval Research (ONR). The event offers hands-on activities and provides middle and high school students an introduction to naval STEM careers and educational opportunities. (U.S. Navy photo by John F. Williams/Released)