This Activity is meant for Cub Scouts.

set of old Monopoly money
a few leaders - 7 or more is better
a bunch of candy or trinkets

Give one leader all the $1 bills, another leader all the $5s, and so on for the $10, $20, $50, $100, and $500 bills.

Gather all the scouts and tell them their job is to make great investments and increase their money so they can buy something at the Trading Post.

First, they need to borrow some money from the bank.
Once they have money to start, they need to find someone that will help them invest that money and exchange it for more money.
They can continue this as long as they want until they have enough money to buy something.
Unfortunately, we don't know where the bank is so you need to first find the banker. He is somewhere in this room and you just need to ask him for a loan.

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The leader with the $1 bills is the banker - make sure you tell him this. He should only give $1 to each scout that asks him for a loan.

All other leaders with money should not show which bills they have. When a person asks to help him invest $5, he should say 'SURE!' if he has the $10 bills or 'NO, you don't have enough money' if he has something else. He takes the $5 and gives a $10 in exchange.

When a scout reaches $500, he should bring his bill to the Trading Post where he can exchange it for some reward.
You can reward those that finish first by having a few more popular items down to smaller things. For example, 5 bags of Skittles, 10 tootsie roll pops, and 50 tootsie rolls.

The Trading Post should have a sign that says 'All Items On Sale - $500 each'. Scouts will probably run to the trading post to see what things cost and most of them will figure out they need to get to $500 to buy anything and they need to get there first to get the bigger prize.

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If you have enough leaders, its better to have 2 bankers and 2 people exchanging each denomination to minimize a huge mob at each exchange.
This also means some investors will run out of bills to exchange and scouts waiting there will need to find the other investor.

You could run it by patrol and have each patrol find investors as a group, each patrol having a single $1 bill to start.