1. The problem statement, all variables and given/known data Linear and quadratic elements differ because of the extra mid-nodes on quadratic elements. Quadratic elements can "bend", linear can't. How do you define the DOF of a element? (see at solution attempt) 2. Relevant equations - 3. The attempt at a solution For example: a linear triangle has 3 nodes. Each node has 2 DOFs (x and y). The total field variable will have 3 x 2 = 6 DOFs? Why does this element don't have 3 DOFs per node? (2 translations + rotation) Wat is the problem with following elements, why is this not possible? What with a quadratic and linear element adjacent to each other. This is not compatible, how can this be visualized? Thanks in advance!