Show Don't Tell

I always used to get confused by the writing advice "show don't tell".  How can you show a reader without telling her about it?  When I'd ask the question, my teachers (and a few colleagues) would look at me that "You're kidding me, right?" expression.

Recently, I've heard the advice described differently — scene (show) versus summary (tell). That I understand. Ideally a writer should enter a scene and allow it unfold for the reader. Although there are times when summarizing what's happened works in a story, many new writers tend to lean on "summary" versus "scene".  

It may have taken me a couple decades to get clear on this, but now that I'm, I'm ready to write some fabulous scenes.  

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