The utility model relates to a variable quadrilateral teaching air, which belongs to the teaching aid, and consists of a ruler, a connection point and a groove. The ruler is provided with grooves, every two rulers are fixed at a connection point through a screw, and the screw is installed inside the groove of the ruler, so that quadrilaterals with different shapes can be obtained by adjusting the position of the screw inside the grooves. The variable quadrilateral teaching aid has the advantages that the teaching aid can be stretched at will, and the shape of the teaching aid can be varied, and the demonstration effect is direct. The drawing operability and the practicability are strong. The variable quadrilateral teaching aid has low cost, simple production and easy popularization.