Retired middle school science teacher Kathie Kelly, of Acton, has found her purpose and passion in the wilderness as a volunteer citizen scientist for Earthwatch.An international nonprofit environmental organization, Earthwatch aims to connect everyday people with the world's top scientists to conduct vital field research. Since retiring as an educator in Stow in 2013 after 20 years, Kelly has worked alongside scientists, researchers and citizen scientists around the world studying animal behavior and climate change since her first expedition with Earthwatch in fall 2014.