These 6th graders at Hill-Freedman Middle School race “puff mobiles” they built using everyday materials like drinking straws, Life Savers, paper, Scotch tape, and paper clips. The activity was a part of Philadelphia’s Science in the School Day event, held in November. Sixty-six students at Hill-Freedman and 115 4th and 5th graders at John Welsh Elementary participated in the program, which is a part of a nationwide effort aimed at promoting and inspiring students’ interest in math, science, and engineering. The event is a part of Cities United for Science Progress, a partnership between the U.S. Conference of Mayors and DuPont.