Class 1: a circuit with a paper button

A circuit is:
a complete and closed path around which a circulating electric current can flow.
a system of electrical conductors and components forming such a path.

http://en.wikipedia.org/wiki/LED_circuit

A LED is:
http://en.wikipedia.org/wiki/Light-emitting_diode

This is a LED on a coin cell battery (3V) with a perspex shap on top of it,

http://www.instructables.com/id/DIY-Led-add-on/

A drawing with a LED is:

A drawing enriched with interactivity of one or more paper switches and buttons where the LED or more than one LED dependent on these switches performs a role in the perception of this drawing. (Beam in e-paper class:-)