This set of magnets are used in the teaching of physical experiments and demos (elementary science experiments, middle school physics experiment) teaching tool. Can also be used for student stationery, children's toys... Real existence and change it can make students intuitive feelings to the magnetic field, but also the vivid expression of its physical characteristics, can arouse students' interest in learning, so that their attention, stimulate their thinking and imagination. It is a great help and promote the primary and middle school students and children understanding and cognition of the magnetic field. Magnetic field beneficial to the human body, children can also use magnets N;S and Earth's magnetic field is repulsive.Principle of opposites