A teachable moment is one of those moments where you can relate some content to something going on.
Like, for example, a hurricane.
We teach weather in the seventh grade, but we're not scheduled to do it for a while yet. We do severe weather late in the year because it's a great one to do for projects, and the kids love it. It keeps them involved when they're starting to think about summer vacation and shut down mentally.
You can show a video of death and destruction (i.e., hurricanes, tornadoes, fires, floods, blizzards, etc.) and seventh graders will sit for HOURS, mouths agape, watching the stuff. It's astounding.
Today I took a few moments in between activities and read a couple of news articles about Katrina. The kids were fascinated. (One kid even had a carload of relatives show up last night from New Orleans.) The dire predictions of the LSU computer forecasters just blew their minds.
I love teachable moments.