Subject: How is the physics of the internal combustion engine best described

Foa a final year project I am making a interactive museum display.  I have cross 
sectioned a real 4-Stroke petrol engine to reveal its inner components which 
will be motorise.  I will also use a computer for annimation and audio.  I have 
researched teaching methods and their application, but would like advice on 
content, language and the best way to explain thermodynamics to a young audience     
Aged 4years+.  Any help would be very much appreciated, Cheers Andy.

Re: How is the physics of the internal combustion engine best described