Thanks SKK! That thread has a ton of great ideas.

My daughter is now 24 and she and her friends loved participating in cooking the meals. I love the answers above. Also loved Amanda asking a question recently on Hotline and what the responses were and what she did. http://food52.com/hotline/14373-no-bake-treat

Thanks Sadassa and Susan for your helpful answers! I am hosting 3 girls plus my own. Will let you know how it goes.

I've just looked back at a series of photos taken in my twin granddaughters' first grade class. There were about 10 children and a teacher. The class made Stone Soup. Kids were given safe knives and a cutting surface, and a vegetable to cut up -- onions, zucchini, carrots, celery and more. All the veggies went in a large soup pot, with rice and seasonings. Then, what looked like a bucket brigade put water in the pot to cover the ingredients. Lid on, the pot cooked away. Last photo shows the empty pot -- all soup served and eaten. The kids looked very happy!
For something like this, since the cooking time is about an hour, but passive, they could make dessert, or play.

Hmmmm that's a challenge, a fun one. How many girls? How much time do you want to spend cooking before eating? As a mother of some very picky [older] eaters, I have to ask how adventurous do you think they are when it comes to food?
I have never led a group of kids to cook, but I am thinking you could either do something where each kid does the same set of tasks (i.e. assembles their own wrap sandwich or pizza) on their own, or you could do some kind of one-pot recipe, like a lasagna or a pot of chili where each kid gets a different task (i.e. one kid grates cheese while one kid seasons the ricotta).
For dessert you could have the girls make their own yogurt and fruit parfaits while the main dish is cooking (if you end up doing something requiring cooking)?
Yes, good luck!