While reading up for a GIS class I will be team-teaching probably in fall of '04, I remembered something from when I took GIS (Geographic Information Systems):

data can be stored in a vector (shape, like a classical map) format or a raster (gridded or pixelated) format. When the prof for the class showed us an example of a map from raster data, I blurted out "Oh! It's just like a chart for a needlework pattern!"

the rest of the (mostly male) class gave me strange looks.

I guess I won't be using that analogy in my class.