Oh I wanna try teaching perspective!
I think the most important thing to remember is that perspective exists, no matter what angle you draw a picture from. Cylinders aren't too hard to draw, and most humans and animals can probably be drawn as various cylinders in perspective.
Anything under the horizon line, and when you see it as a cylinder, you'll be looking 'down' on it, and anything above, you'll be looking 'up' at it. If you think of things as tube-ish it gets easier.
Applying basic perspective to cubes/boxes etc is something really easy that you can look up tutorials for everywhere =O Alternatively, you can just make it up and hope it looks okay. I do that.
If you're going for technical perspective, I recommend learning to do 2-point perspective. You can do a lot with it.
Lame example picture --->
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