Math Door Handles (Indirect Homework 2)

I am all about assigning indirect homework. Indirect homework, to me, is simply learning in small intervals without the student directly knowing they are learning. To do this we must be sly ;) We must be crafty, clever teachers who give students something mathy to use in their room or their daily lives.  How about a door handle?

Now, this need not be basic. It can be definitions, pictures, problems, etc. Yet, it needs to be stripped down to the essentials so that the student can make small glances at the picture multiple times per day and learn. Aggregate these small amount of learning over the weeks, months, and year and you have your extra homework :)

Thoughts?