This study provides educational implications for discussion education by exploring elementary school students’ interruptions in group discussions. In total, 17 group discussions in 4 different classrooms were observed and audio-taped. Collected data were transcribed and analyzed in three different categories (function, format, and agents of the interruption) and several sub-categories were extracted to show multi-faceted aspects of interruption. The results show that interruptions in the elementary school classroom discussions occur very frequently, in various ways and in non-cooperative manners. Thus, systematic education to correct this is indispensable. Contents and specific teaching plans and strategies regarding interruption are discussed and topics for follow-up studies are suggested.