The instructor and students do a skit where students represent quantum states that are “measured” by the instructor resulting in a state collapse.
The instructor ask for volunteers for an activity that is a conceptual play of what happens during a quantum measurement.
The instructor can remind students of the prerequisite understandings as a lead into the activity.
The instructor selects the projection operator corresponding to the result and lets that operator act on the state.
\[\Big(|+\rangle_y \;_y\langle+|\Big)|\psi_{student}\rangle\]
The student renormalizes their state.
\[|\psi_{new}\rangle = \cancel{_y\langle+|\psi_{student}\rangle}|+\rangle_y\]