I did this with a group of girls age 9-11. There were 6 girls. I did memory wire bracelets rather than necklaces. I cut all the wire in advance and made a loop in one end. I got a bunch of inexpensive beads together (stone chips, glass bicones, fake pearls, those plastic cube beads with letters on them) and just put them all in the center of the table for them to choose and make their own thing. I made one ahead of time so they could see one finished, and figured if any of them were having trouble making their own pattern, they could copy mine or do something similar. None of them had any trouble choosing which beads they liked or coming up with their own design. They loved the letter beads.
I gave them all a small bowl to put their beads in, and cloth placemats on the table to keep the beads from rolling around. I just gave them basic instructions on how to string the beads and to leave about a quarter inch at the end of the wire to turn a loop. When they were finished, I just turned the loop for them and they had a finished bracelet. They all had a good time and nobody had any trouble. It was really fun!
Erin