If you are not willing to do the math, do you really deserve the profits? When you are investing in such a highly leveraged investment, it's important that you understand the basics of the trade, the value of what you are putting into it, what you are getting out of it, and all of your potential loss scenarios.
Go on a counting scavenger hunt! For young children, you can keep the hunt simple and indoors, go on a hunt and count how many bedrooms, windows, doors, bathrooms, etc are in your house. For older children, you can even take this adventure outside. Look for certain kinds of animals, plants, flowers, you name it! Add in another element of fun (for any age) and create a graph for them to track their finds!
The trade worksheet helps put you in control of your trading. Calculating your profits and losses ahead of time lets you know if the risk you are taking is a risk worth taking. This is how you gain control of your trading. You become prescient on whether the opportunity you are taking is a good one or not. This puts you ahead of the majority of traders who simply fly by the seat of their pants.
Go Shopping! : You can cater this to all different ages. For young children, you can do a 'mock shop' and let them pretend to go shopping in a pretend store (your kitchen). Label certain items with easy to read prices and print some pretend money for them to shop with! For older children, you can let them help you in the actual grocery store with a specific shopping list. You can even set specific spending limits and give a specific amount of items and let them determine what they can afford, etc.