Abstract: Calculus of Variations derives conditions for finding maxima and minima of functionals (“functions of functions”) by slightly varying a function (here it is the input) to see how the functional value reacts. We will derive the Euler-Lagrange equation and see it in practice, finding the curve of a soap bubble over two rings and the brachistochrone. If time allows, we will look at generalizations of the Euler-Lagrange equation in higher dimensions.