What is the easiest-to-explain way to read a QR Code? What is the easiest way to teach/enable someone else to read a QR Code?

Please notice, I'm not asking how to read a QR Code. I know there's a lot of apps to do it.
I'm asking what is the easiest way to enable someone else, perhaps someone without much technical knowledge, to scan a QR Code?

For example, this would be great if it actually worked:
http://www.labnol.org/software/scan-qr-code-with-google/27955/

It does not require downloading an app, therefore it's easier to show someone how to do it.
Unfortunately, for the 2 android phones I tried that on, it did not work. (there was no image search option as described in the post)

Is the easiest way really to have someone download an app and run it?
Yes, just download an app and run it.  You can't visually look at a QR code and decode it with your brain.