Matt Krigbaum (left), a teacher at Mitchell Elementary in Ann Arbor, Mich., pours water from the Pearl River into a turbidity tube to measure the river's light penetration. Krigbaum, along with Lois Williams, principal at Elizabeth Courville Elementary in Detroit, Mich.; and Carolyn Martin and Arlene Wittmer, teachers at Elizabeth Courville Elementary; conducted the experiment during a GLOBE (Global Learning and Observations to Benefit the Environment) hydrology workshop. GLOBE is a worldwide, hands-on science education program in which teachers can become certified to implement the program at their schools after taking hydrology, land cover/biology, atmosphere/climate and soil protocol workshops. Twelve teachers from across the country attended the recent weeklong GLOBE training at SSC, offered through its Educator Resource Center and the NASA Explorer Schools program. All workshops are free and offer continuing education units.