What, exactly, is an electron

I know it's a subatomic particle with a negative charge that orbits around the nucleus of an atom... well that's what I've been learning from elementary school to 9th grade, but my 10th grade Chemistry book talks about electrons as if they were waves... but they have mass? My book illustrates them as squiggly lines rather than dots like I've been used to seeing, and I don't understand why it's illustrated like that. I asked my teacher and he said "because it's a wave". He either did a really poor job of explaining it or I just failed to understand what he said... probably the latter.

So, what EXACTLY is an electron?

you've heard of photons right? tiny particles of light? but light has wavelike properties too doesn't it? Isn't that just as confusing?

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This all start with the infamous double slit experiment. imagine a wave approaching a slit
http://en.wikipedia.org/wiki/File:Wavele…
notice the wave striking the wall on the right?
imagine stopping the wave instantaneously. You'll see about 7 different places where the peak of the wave is striking the wall giving this diffraction pattern

now imagine 2 slits where you get interference
http://en.wikipedia.org/wiki/File:Young_…

now go to this site
http://phys.educ.ksu.edu/vqm/html/single…
pick electrons, 100eV and 15nm slit width and click start
you can see the main band of electrons in the middle and some scattering. If electrons we're simply particles, you wouldn't expect and scattering.

now try this site...
http://phys.educ.ksu.edu/vqm/html/double…
click on electrons, 100eV and a 10nm seperation.
you clearly see a constructive and destructive interference patterns as you would expect to see with WAVES!
if electrons were mere particles, they would go straight through without the interference

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now here's one of the most stangest things known to man. If we designed that experiment to fire 1 electron at a time through a 2 slit setup, which has been done countless times fyi, we know that electrons are like a particle because we're shooting 1 at a time. And we would expect the electron to pick a slit and head on through. but it doesn't It starts as a particle and behaves like a wave by going through both slits at the same time and interfering with itself.