This is a simple introduction to getting students comfortable with conversing. It may seem basic, but I suspect students feel less comfortable talking with each other then we realize. For older students, consider adding sophistication to the sentence stems.
I launched my students into a jigsaw without first teaching them good student-to-student communication skills. That didn't go well. Here's a great way to build those up so that students are more effective when they teach each other.
Check out this author's jigsaw "how to". Heed my advice (ie- learn from my mistakes!) and don't sacrifice depth for breadth. Give students smaller chunks to insure that they are really diving deep and just not "covering" the material.