The assumption is made that distortion of a thin plate loaded transversely to the plane of the middle surface of the plate can be described in terms of the curvatures of the middle surface. These curvatures are given as second derivatives of the transverse deflection u₃, and it is thus important to the understanding of plate theory to establish the transformation laws for the components of the curvature tensor under rotation of the axes about the x₃-axis. The Mindlin theory of plate bending is a plate theory which allows for shear distortions in a manner that is applicable to moderately thick plates. The theory has application in some finite element formulations. Bending moments in a plate are related to curvatures given as second derivatives of deflections. The isoparametric plate elements attempt to model the plate theory in a way similar to the discrete Kirchoff with loof nodes elements except that the shear constraints are not applied.