Explicar con plastilina.
My girlfiend has just explained what 'to explain with Plasticine' means.
Do you know what it means? Is it a common expression?
Ignoring the context, the meaning of the phrase, is to explain someting in the most simple way possible. The word "plastilina" is a form of modeling clay, and as used in the phrase , would express "so simple a child could understand"
Interesting - so would it be more or less the same as when you say in English 'Do you want me to draw you a picture?'