If you give your child lunch money only later to discover they are buying candy with it you may discover your yearning for a special less fungible lunch currency. Not surprisingly there are micro-currency solutions for this problem.
Meanwhile, back on the lunch money problem. You could send your child to school with lunch already made. This would teach them valuable negotiation skills as they barter their lunch for better options. A wise parent might just send them to school with some highly fungible trade goods — cookies for example.
Back in my school days, I was in the subsidized school lunch program. This meant that my parents pre-paid lunch for the week, and I received a card valid for a certain number of lunches. On the days when the school lunch was nauseating, such as when corn dogs were served, I would trade my free lunch for cash so I could purchase something a little less disgusting.
The school lunch card was not transferable, but the meals purchased with that card were. After purchasing the lunch, I could trade the whole tray for 75¢, or just the approximation of pizza for 50¢, and then purchase Hershey’s strawberry shortcake.
According to the U.S. Department of Agriculture, the school lunch program
Provides nutritious lunches and the opportunity to practice skills learned in classroom nutrition education.
Skills like economic decision-making and negotiation.