Note: If possible, ask girls to bring the names of their grandparents to the activity. Also have them prepare a family story to share (about a grandparent, parents, family tradition, ancestors, etc). They need to be able to tell it, NOT read it. If they would like they can bring a visual aide. For example, my husband's grandma found hundreds of snakes in her house when she was a widow and living alone. Her bravery in staying to fight the snakes got her on the national news. I loved this grandma, she was an inspiration in lots of ways during her life, I'm always telling my kids about her. If there isn't time for advance notice, you could always have the girls share a family story about a favorite tradition, vacation, a favorite grandparent, etc. They could guess on the grandparents and correct it when they get home.
To start, have a lesson/discussion on how performing temple work and doing family history work blesses families.
Next help the girls fill in the first three rows of their pedigree chart, the great grandparents are a bonus if the know them!
Here is a pretty pedigree chart I saw on About.com
Print a family group record for each girl to begin filling in.
We finished this activity by giving the girls popcorn, twizzlers, and leftover halloween candy to munch on while everyone shared their stories. They had so much fun telling stories, there was no need for either of us leaders to share a story although we were ready if time allowed. Simple, meaningful, easy activity, I loved it!