In this chapter, deflected beams and plates are studied. It is shown that, for both elements, it is possible to define the deformation characteristics by derivation of the components of the generalized displacement vector, which, in addition to displacements in the strict sense, also presents rotations. Analogous with the 3D solid encountered in Chapter 8, it may be noted that, also for the 1D or 2D solid, the static operator is, but for the algebraic sign, the transpose, or rather the adjoint, of the kinematic operator. This property of duality proves of great utility in the case of discretization into finite elements.