Air Force Cadet Yaira Diaz helps third grader David Acosta, 8, build a bridge using plastic straws Feb. 22 at Evans International Elementary School in Falcon School District 49. More than 50 cadets arrived from the U.S. Air Force Academy to explain careers in science, technology, engineering and mathematics. They covered six academic concentrations during the school's STEM Day: physics, along with mechanical, electrical, civil, aeronautical and astronautical engineering.