It's kind of fitting that as I work on managing our money well and living frugally that I incorporate that in our Girl Scout troop. I'm no expert, I go against my own advice, and I continue to learn from my mistakes. I don't think any of this makes me less suited to help teach the basics of money management to children, in fact I think that it helps me a bit.
One way I did this was through making paper checkbooks so we could practice balancing them. These were pretty easy to make. I cut loose leaf paper down to size, cut construction paper (big enough to fold over the loose leaf), stapled, and folded. Making over 50 took about 1.5 hours.
First we talked about how money got in the bank accounts, then about how when we used our checks or a debit card that the amount of money we had in the bank changed. They got to pick their own starting balances (some were reasonable, others had high hopes for their future income) and we talked about the expenses that would be deducted. I brought up how much Girl Scout dues were, how much it costs to live in our area (and how the costs have changed over the years) and let them pick their expenses.
This along with picking a career (and making a puppet for that) and making a wallet + Brownie Bucks or Daisy Dollars (and buying their snack for the evening with those), were fun ways to introduce this concept to the girls. I also mentioned how we as leaders have to budget the money in the Girl Scout account as well so that we can do fun things all year rather than just a couple big things and have nothing for the rest of the year.
It was a good lesson for me as well, while working I have taken the easier route for some things and my husband and I have had miscommunication about bills, so I need to take my own lessons to heart ;)