Alternative to remember area and circumference of a circle

Many people can actually remember either:

$pir^2$ or $2pir$

But need a nudge to remind them which is area and which is circumference.

To remember which is which:

Just remember $r^2$ must be an area

And a single $r$ must be a line

So

$\pir^2$ = Area

$2\pir$ = The line of the circumference