The other day I was explaining to a friend how a camera works. It’s a simple and old analogy, but she said he helped her understand very easily. Think about the components of a camera as such;

Blink - Shutter
Pupil - Aperture
Color - ISO

Now imagine the camera as an eye - How fast you can blink (more specifically reverse blink) is how quickly the shutter opens and closes. Depending on how dilated the pupil, will let more or less light in; aperture. And the colour of your eyes relating to light sensitivity, blue eyes = 400ISO, brown eyes = 100ISO. 

Pretty simple, but thought I’d share.