On January 22nd I wrote about taking your children to work as it lets them see how you earn money and that it doesn't come from the ATM.
The next time your kid turns his nose up at the meal you prepared, take him to the grocery store so he can see how much you spent on the meal. The grocery store is another great place to take your kids so they can learn about money. Here, they'll learn the price of things. Notice I didn't say cost. The cost is the velocity the dollars roll into your pocket, the price is the velocity they roll out of your pocket. For any given item, they are rolling out at the same speed (price), and the grocery store is a great place to demonstrate this activity.
First of all, plan the meal and make a list of the items you need for the meal. If your child sees you're going to the store and have a list in hand, that will teach them organizational skills. It's important to stick to your list and not buy anything that isn't on your list. Your children will see that too, and it will make an impression on them.
It is important to comparison shop. Let them see that you don't simply buy an item because it is convenient to reach. Look at the choices; they will see that you're using your judgement and that will also make an impression on them, not just at the grocery store, but everywhere else.
Just as important, they will see all the ingredients that go into the meal, and yes, the price of those items as well. They will see that it is an orchestration of sorts and all the effort it takes just to deliver the meal to the table.
If you want to take the lesson further, and you think your child is ready, have them plan the meal themselves (not one that consists of Frosted Flakes and pork rinds, but a wholesome one.) Have them make the list of the items needed that aren't in the house (they may need help with this,) and then go to the grocery store. Have them compare the choices of items needed, and make sure they stick to the list. If you really want them to learn a good lesson, give them a budget; tell them they have $20 to spend. They'll learn a lot; if anything, this lesson will keep your children occupied at the grocery store.
When's the next time you're going to take your kids to the grocery store?