Kim Hui-ryeong, a senior researcher with the Korea Atomic Energy Research Institute, is explaining why air is expanding through experiments in a classroom of third-graders on April 7. He is the father of Kim Dong-wi, a third grader in Daedeok Elementary School in Yuseong-gu, Daejeon. The school has been running scientist parents classes since 2004, taking advantage of having many scientist parents working at the Daedeok Research Complex.