For all demonstrations that involve him writing code, it is probably worth asking him to use JSFiddle: http://jsfiddle.net/
A client wants some text scrolling horizontally across the page. Write something to do this for him.
- Bad answer: Code uses the tag. It is a bad answer as the marquee tag isn't standard, and technically doesn't exist.
- Good answer: He simulates the behaviour of the marquee tag in JavaScript. Minus points if he uses inline style or javascript.
- Best answer: He tries to talk you out of it.
Explain to me, a backend developer, what the most recent relevant article you read was about.