Many years ago, my daughter wanted to open a lemonade stand. Without a lot of thought, I assented. We made a quick pitcher of lemonade, I handed her some cups to go with it, and she scurried outside to set up shop.

About an hour later, my aunt and uncle arrived for dinner. They came in the house four dollars poorer, carrying cups of suspiciously light swill. It didn’t look like the drink we had made, so when my daughter came inside, I gave her the third degree on her business operations.

That little stinker had taken matters into her own hands. Rather than charging $0.25 per cup as agreed, she had increased the price to $2.00. She pressed her brother and the neighbor girl into service, with one flagging down cars and the other selling the drink door to door. When they ran out of lemonade, Miss Industrious simply inserted the hose into the empty pitcher and filled it with water–and continued to make sales. $2.00 for a cup of lemony-scented spigot water, and she was raking it in. While I secretly admired her industriousness, I questioned her business ethics.

The next time my daughter told me she wanted to open a lemonade stand, I was determined to make it a learning experience.

I agreed to let Miss Industrious restart her business, but on my terms. Rather than simply raiding my pantry, we went to the grocery store to buy cups and lemonade mix, as well as posterboard for her signs. Eight-ish dollars later, we trotted home with her supplies and an understanding that she had to repay me for the $8 business loan from her revenue. (She also knew that if she ran out of drink, she had to use the mix we bought to make more–no bait-and-switch tactics this time!)

The next morning with her signs lettered and her lemonade mixed, she was ready to sell. I gave her babysitter the rundown of my expectations, with instructions to keep Miss Industrious adherent to the rules. I went to work and left them to it.

When I returned, I asked how the day had gone. Miss Industrious proudly told me she had made twenty-something dollars. (I don’t remember the exact number.) Rather than congratulating her immediately, I reminded her that she owed me eight–she hadn’t “made” 20something, but rather 20something minus eight. The most important lesson, I thought, was the economic principle.

As usual, I was wrong.

Instead of handing me eight dollars, Miss Industrious handed me all her money. You see, I was preparing to participate in a charity bike ride to benefit cancer research.* The event requires several thousand dollars per rider in fundraising, and her plan all along had been to help me raise money. Here, Mom, she said. It’s all for you. It’s for the PMC.

If she learned a lesson that day, I learned a bigger one.

I may have taught her economics, but she taught me heart.

*If you haven’t heard of the Pan-Mass Challenge, check it out at pmc.org. I don’t ride anymore–192 miles in two days are too much for my knees–but the event remains no less worthy. In fact, it’s pretty amazing.