How to teach HS students HTML & CSS in 1 hour?
jqueryin: I'd keep it fairly brief, trying to explain the difference between block level and inline elements. I'd focus on a standard header/body/footer type layout with usage of an H1, body, span, and p tags.  You can throw in an em or strong for the sake of demonstrating more tags, but you've only got an hour to try and get the basics engrained in their heads.Once you've mocked up the page with absolutely ZERO styling, it's time to delve into the CSS.  I'd show them the basic selectors for background-color, color, height, width, and some font styling.  If you have time, demonstrate padding and margins.Lastly, time permitting, throw them a curve and demonstrate floats, relative positioning, or absolute positioning.  This really might be overboard for an hour.. so it's merely a suggestion.