A teaching demonstrator capable of measuring positive and negative conductivities belongs to the field of demonstration of teaching apparatuses. The demonstrator is composed of a switching stage, a negative
electricity identification stage, a negative
electricity amplifying stage, a negative
electricity display amplifying stage, a negative electricity cursor and voice indication stage, a positive electricity identification stage, a positive electricity amplifying stage, a positive electricity display amplifying stage, a positive electricity cursor and voice indication stage, an oscillation stage and a display stage; the switching stage comprises a
changeover switch, a test rod interface and a testboard; when a measured object is connected to the switching stage, the negative electricity identification stage and the positive electricity identification stage identify positive and negative charges, after amplification, the cursor and voice indication stages are started according to the
weakness of the charges, the display amplifying stages start the corresponding display stages, and the magnitude of energy is reflected accurately via the display stages and the cursor and voice indication stages. A multi-display effect is realized, teenagers can known the
conductivity condition and understand concepts and meanings of conductors, resistors and insulators, and the demonstrator can be popularized widely in schools.