This lecture is best done by transitioning from the final answer of the Lorentz Force and Work on a Rectangular Loop activity. The term in the final answer contributed from the magnetic dipole moment can be singled out. Then, the general expression
$$U=- \vec{\mu} \cdot \vec{B}$$
can be written on the board.
In words, the magnetic dipole moment is a measure of how much the current-carrying object's surface normal (which faces the same direction as the magnetic dipole moment vector) wants to face in the direction of the magnetic field.
Classically, it would be expected that, in the case of the Stern-Gerlach experiment, the silver atoms would all have “rings of charge” (their single shell electron) facing with their normals in random directions. However, the results of the Stern-Gerlach experiment do not reflect this.