Modeling in science has been studied by education researchers for decades and is now being applied broadly in school. It is among the scientific practices featured in the "Next Generation Science Standards" ("NGSS") (Achieve Inc. 2013). This article describes modeling activities in an extracurricular science club in a high school in Korea. The club, founded in 2000, is named ButterStar, with "butter" referring to butterflies (and biology) and "star" representing Earth and space science. The ButterStar modeling activities were supervised by a teacher (the second author) in collaboration with a university-based science education researcher (first author). Although "model" has many definitions (Bailer-Jones 2009; van der Valk, van Driel, and de Vos 2007), the authors view a model as a representation of a target phenomenon or idea using symbolic resources such as drawings, diagrams, physical materials, mathematics, or combinations thereof (Oh and Oh 2011). Here, they focus on how ButterStar students used two types of modeling--data modeling and theoretical modeling--in their observations of sunspots.