The invention relates to a convenient-to-adjust teaching instrument. The instrument comprises a bottom plate, a lead screw, a supporting disc, a supporting plate and a blackboard, a supporting tube isarranged on the upper side of the supporting plate, a lower ring disc is arranged on the upper side of the supporting tube, an annular groove is formed in the upper surface of the lower ring disc, arolling body is arranged in the annular groove, an upper ring disc is arranged on the lower side of the middle of the supporting plate, the lower side of the upper ring disc is in contact with the rolling body, a left supporting frame is arranged on the upper side of the left portion of the supporting plate, a third bearing is arranged on the left supporting frame, a left blackboard rotary shaft is arranged on the inner side of the third bearing, a right supporting frame is arranged on the upper side of the right portion of the supporting plate, the right supporting frame is provided with a first bearing and a second bearing, the inner side of the first bearing is provided with a first gear rotary shaft, the left side of the first gear rotary shaft is provided with a first gear, the rightside of the first gear rotary shat is provided with an adjusting knob, the inner side of the second bearing is provided with a second gear rotary shaft, and the right side of the second gear rotary shaft is provided with a second gear. The instrument has the advantages that the structure is reasonable and the application range is wide.