wow, buddy Im with you. I am experienced in a little of tit-bit of electronics but getting to interface a mc and a LCD is on my 'ToDo' list!
ash is correct, it does involve an extra level of sophistication, and before you get into this level, you have to go through the basics too. Like interfacing a microcontroller and programming it etc.
There is no simple way, albeit a cheap one - maybe. But if you and your son like to spend a few months learning something exciting (for now doing something simple for this year's science fair) then go ahead and buy yourself a microcontroller kit.
The link here get you to a site which gives you the kit to interface a LCD screen.
http://www.mikroelektronika.co.yu/
http://www.mikroelektronika.co.yu/en/tools/easypic4/