10.5 Exercise 5

The moment of inertia of a long rod spun around an axis through one end perpendicular to its length is $m L^{2} / 3$. Why is this moment of inertia greater than it would be if you spun a point mass m at the location of the center of mass of the rod (at L/2) (that would be $m L^{2} / 4$)?