老师用一个地球仪向学生们展示了不同国家的位置。(Note: This translation uses 地球仪 (dìqiúyí), which means "globe" in the sense of a spherical map of the Earth. It avoids the potential confusion with 灯泡 (dēngpào - light bulb) which is another meaning of 'globe' but doesn't fit the context.)