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 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.
You are also able to figure out risk management scenarios while using it. The trade worksheet helps to narrow down your focus and gives you a level of comfort on what can and might happen regardless of the outcome. You design hedge scenarios along with speculation scenarios together to make it work to the best of your account's ability.
Get in the Kitchen! I was very hesitant for a while with my son when it came to the kitchen. I worried about the GIANT mess that would be left when he was done "helping". You don't even have to take on the entire project with them! You can start small and let your child help with measuring certain ingredients. You can modify the difficulty of the 'lesson' by talking about the different kinds of measuring cups and seeing what other measurements can also add up to equal one cup, etc.