students should be aware of the many semantic problems caused by trying to describe QM behaviors with words that pre-existed the study of QM. 1) there is no such "thing" as a "wave". The word "wave" is a description, or name, for a pattern that is periodic - it repeats at regular intervals. "The wave (at the seashore) knocked me down". That burst of water that periodically surges on the beach is called a wave by convention, but it is not a wave, and neither is that single burst of water periodic, but observing and measuring and then graphing the ocean swells does result in a graph with a periodic attribute.
2) electrons, photons, etc are not particles. The word particle was defined well before QM and means a discrete little thing with finite dimensions AND was once part of something larger. The early QM explorers would have done all of us a favor by making up a new word.
3) there are no "packets" of energy. Packet was already defined as a small enclosure, fully sealed, if only by a drawstring, and that which was inside the packet was not outside the packet. With energy, the "field" (semantics again!) it is said extends forever, getting weaker according to the distance from the concentrated center. "spot blur" would be better than "packet". things can be delivered in packets, and so by that part of the the definition of packet the use of the word packet to describe a bit of energy is somewhat accurate.
On to double slit experiments: whatever an electron (or photon) is, it (may not be an it) can be isolated, toyed with, put to use, turned into profit. That profit can be had at least gives it cash value. When the electron is fired from a so-called "gun" at a double slit, or at a fine wire dividing a space in two (Hitachi double slit), the target is missed as often as it is hit. Crappy gun. You want to be asking why such bad markmanship? And when the misses pass on to the target, apparently they don't travel in straight lines. 795
You want to ask why not straight? The complete trajectory of the electron is not known. Some may be curve balls, other sinkers or even knuckleballs, and a few seem to be hardballs. why? After each electron hits the target, (in a drunken state, it seems), that's it for that electron. The next electron hits somewhere else on the target, and that's it for that electron. It IS curious that after a lot of pitches have been thrown that the hit points do look like what we call a wave, but by no means does that mean photons or electrons are waves, as wave is not a thing but a named pattern. Apparently the electrons or photons have favorite trajectories. It is that which requires explanation.
As for "observation" which is just a general word for "measurement". Once we know why the electrons or photons or etc have favorite trajectories, it may be easier to explain the clumping-spray pattern seen when measurement apparatus are brought into play. It seems that once the measurement apparatus (pardon my French) "f*cks" with the electron, etc, it goes into a tumble, like when a spinning top which is on some trajectory is knocked over.
For whatever reason, in the physical sciences leading up to the time when the little ones were first found and named, an assumption was in place that all was "particle" or "wave", and so that expectation was foisted upon the little ones. That was a blunder. The blunder was never fixed, but words like "wavicle" were an attempt at a fix.
And note: the "wave function" does not "collapse". Bridges collapse, functions sometimes cease to be useful. And the measurement apparatus does not "destroy" the interference pattern, rather it changes the pattern of electrons on the target. Such really bad choice of words!
And I want to repeat what others have said: none of this has to do with human consciousness becoming aware of the measurement report. Once the measurement apparatus is turned on, the wave-like pattern goes away, and the spray-clumping pattern begins to manifest whether anyone is there watching or not. I liken it all to a good who-done-it story, and not a fantasy. 795