Shut up and calculate! 

The only viable approach to teaching Quantum Mechanics in college is "Shut up and calculate!"

The alternative is chaos.  Imagine a class where every kid is allowed to ask those questions that are not allowed, and embarrassed professors have to admit "We can't explain how or why, but we do get exactly the correct result."  The "Copenhagen" interpretation of Quantum Mechanics doesn't allow certain questions because according to this theory there is no answer.  

For example, in Quantum Mechanics  a particle doesn't have a classical trajectory.  Trajectories don't exist.  They can't exist.  Numerous reliable experiments have proven that all hidden variable theories (such as classical trajectories) don't agree with reality.  A particle goes from A to B but don't ask where it is in between.  The question is not allowed because it's not part of this theory.  You are not allowed to draw a line from A to B.

How does one particle go through both slits?  "We don't know how, but we know that it does."  That's just the way it is.  Get used to it.  The theory agrees perfectly with statistically measured results. 

Where is the particle now? "We can't know that."  It's not possible to answer that.  The particle doesn't have a position or velocity or shape or size or any property until it is detected (measured) at location B.

So what's the problem with our "Shut up and calculate" approach?  If it works, don't fix it, right?

Picture a single atom that emits a photon.   The photon's Schrödinger wave spreads out in all directions at the speed of light.  Two million years later that photon (from Andromeda) happens to get detected in my telescope's image sensor.  The whole, undiminished photon showed up and made a bright dot.  The probability was 1E-29, but I got lucky!  

On the other hand if we assume that light is a pure classical electromagnetic wave it would have spread out in all directions and only a very small part of it (1E-29) would arrive at my detector.  That's way below any image detector's threshold.

Both pictures give the right answer statistically because the Andromeda Galaxy emits a very large amount of light.  But the wave picture lets me imagine the process in my head.  The particle picture makes me wonder exactly where was that photon for two million years?  (...But I'm not allowed to ask).

M31: The Andromeda Galaxy [NASA]
Credit & Copyright: Robert Gendler (robgendlerastropixs.com)

And how can I imagine my telescope lens focusing "statistical probability information?"
That makes no sense!