Teach them how to sew on a button and how to hem (shorten) something. I taught my Cub Scout den those two things, and their mothers wept with joy. Even with all our modern, easy-care clothes nowadays, those are the two things everyone should know how to do.
Also, depending on how many girls there are and your work space, teach them the basics of cooking and baking simple things. Their future husbands will weep with joy.
This sounds like fun -- and a terrific age for you to work with!
How about career day. You could start group by asking them to write down what they want to be when they grow up. After review, you could get some female examples to hold a question and answer session.
Great age to talk about diversity. After talking about cultures different from their own. They could make posters to display around the school illustating what it means to them.
You could, as a group, write a childrens book. Have copies bound and soforth. Every girl could have a copy. (small fee could apply) All of their names listed as authors and illustrators. Keepsakes for any parent for sure.
There are also other types of simple musical instruments that kids can make.
I realize that I'm "tooting my own horn" here, but I just wanted to stress that doing something musically, concerning a craft, can teach a child about a lot of things.
As a child I always loved show and tell. You could have pet day. They could bring a picture of their pet. Talk about the needed care of them. They could exchange funny pet stories.
(hope Im on the right track... I just keep coming up with stuff)
Pen Pals! Have them write letters to girls, their age, in different countries. Who doesnt like to get mail? I remember being so excited when I would see my own name on an envelope.
Not so excited now... this guy Bill keeps sending me letters. lol