  Students in a quantum mechanics course are often introduced to the
Schr\"odinger equation as the standard mathematical tool. However, rarely do
students develop an understanding as to why the equation is the choice for
modeling quantum phenomena or where it came from. While many books do have a
heuristic derivation, they sometimes differ in their approach and often fail to
give a satisfying explanation to the so-called canonical substitution of
momentum. In this paper, we use de Broglie's hypothesis along with experimental
results and theories to provide a heuristic derivation of the Schr\"odinger
equation and of the the momentum operator.
