This presentation makes it so clear through clear step-by-step animation that students get it the first time. I walk them through the process using the presentation all along, and I get none of the bewilderment that used to plague my initial jigsaw attempts.
In the first slide, students are represented by circles in their original groups. Then the circles are numbered, and the animation shows them moving from their original groups to groups based on their numbers. At that point, each circle turns into a puzzle piece, illustrating that in gaining knowledge about their specific topic each student has become part of the puzzle that will be completed by their whole original group when they reconvene. The last click sends all the puzzle pieces back to their original spot, all puzzles completed.
I included notes of what I say at each step. Really simple and clear, and I use it with great results year after year!