Elmo? SpongeBob? A children's book by Wellesley's Katie Smith Milway is all about microfinance. And it's a hit.

What gave you the idea to write One Hen?

 I said to my publisher, Kids Can Press, I wanted to have a positive midlife crisis, and that was going to be putting more energy into writing kids' books. They knew I had a background in international development and asked if I would write a book that would introduce kids to that world. Microfinance was a natural, because it creates development and alleviates poverty in ways that any child who'd run a lemonade stand could understand.

So it wasn't that Muhammad Yunus, the founder of Grameen Bank, won the Nobel Peace Prize for his work in microfinancing?

I sent the manuscript in the spring of 2005. We could never have predicted that Yunus would win the Nobel Peace Prize [in 2006].

The book is based on the true story of a boy who used a microloan to start what became the largest poultry farm in Ghana.

Where did you find him?

I heard Kwabena Darko speak at a microfinance conference, and his story struck me. He managed to go from very small to creating a business that transformed his country. I thought if kids could see that you could start something as a child that could eventually help an entire country, it would be powerful.

Did you work with him on it? I didn't meet him until later. This story is based on his life, but every single word is not exactly his life. I drafted my piece based on his bio and things I knew about microfinance. Then I tracked him down and asked him to read it.

What did he think of it?

He saved me from myself! He told me, "Katie, I wouldn't use my first funds to buy a rooster. If you want your hens to lay eggs, you don't want a rooster around." I also had the mother growing strawberries in the garden. He said, "We don't grow strawberries in Ghana. Try pineapples!"

How many hens do your kids have? I don't think they let you keep hens in Wellesley.

What's the point of microfinance in a rich place like the United States?

According to a Texas A&M study, the spending power for kids 4 to 12 is $30 billion -- and they influence $600 billion of their parents' spending. Just half a percent of that range is $150 million to $3 billion. That could go a long way to funding microbusinesses.

Why has this caught on with teachers?

Teachers are looking for ways to make social studies more real, and this shows you what modern-day life is like in Ghana. It also covers math and reading. It has a website, which is great for keeping kids' attention. And the unfortunate financial crisis has led teachers to look for ways to teach kids financial literacy. It's also written on two levels, so it can work for first-graders up through middle schoolers.

What's next for you?

People keep saying, "Take this to scale." I've got a job, I've got kids. But I've been blessed that things have kind of fallen into place -- people have volunteered to do things like marketing and curriculum development, and now when people ping me, I can direct them to these teammates. In January, we incorporated as a charity. Now we need to raise $300,000 to hire a skeletal staff, people that want to institutionalize it. I'd love to stay involved.