I love the "Get the Gist" lesson format, and it's a great way to get students of all ages (with adjustments for grade levels) to get the idea of summarizing.
Basically GtG works like this:
Students read a piece of a passage--I suggest starting with a "meaty" paragraph and work your way up to sections and finally a complete passage.
(Keep the I do, We do, You do lesson format in mind.)
Start with lots of modeling of the process, then let students have a go.
After reading, students use a white board or other tool where their writing can be easily edited. Students work to put together a sentence with no more than 10 words that covers who or what the piece was about, plus the most important point to remember from the passage. They can work in pairs, small groups--whatever works. Then, students compare their summary sentences and decide how they can improve their own to come up with the best summary.
I've used GtG with first graders with stories they've read, up to 5th graders reading their science textbooks.
There's even a song to the tune of The Addams Family song that will help kids remember the steps:
Get the Gist! (snap, snap), Get the Gist (snap, snap)
Get the gist, get the gist, get the gist!! (snap, snap)
It's the who or the what, then the most important thing--
In ten words or less
And then you've got the gist
Get the Gist (snap snap)
A couple of rules to remember: Names (like Little Red Riding Hood or Thomas Jefferson) count as one word. The final statement has to be a complete sentence--stick to the ten words rule.
As your older kids get savvy with this, you can have them write their finalized summary statements for parts of, say a chapter in a book, on post-its. Then, when they finish the whole piece, they can use those post-its to write an over-all summary of the chapter.
Try it, and let us know how you like it!!
Here's a llink to a GtG lesson the the Read, Write, Think site that probably explains it more eloquently than me 
.
