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The Business Guinea PigsA FLITCH brand
Four real guinea pigs · Books for kids 10 and up · German and English

Economics that makes sense. As a story, not a textbook.

Rocky usually has a plan already. Mr. Grey knows the history behind it. Toffy asks whether it's even fair. And Mojito, of course, has read the fine print. Together they explain money, prices, companies and the government in a way that actually makes sense.

The books are on Amazon and in the FLITCH shop. Their world lives here.

The four Business Guinea Pigs: Mojito, Mr. Grey, Rocky and Toffy

Welcome! The Business Guinea Pigs is a bilingual book series: every paragraph in German, with the English right below it. Kids read the story in English and pick up German along the way. The rules and numbers on this site are the ones that apply in Germany.

Guinea Pig Post

Fresh from the enclosure

The latest from the real guinea pigs, the series and the printables.

From the enclosure · October 11, 2026

The Business Guinea Pigs move into their winter quarters

Today Rocky, Toffy, Mojito and Mr. Grey moved out of their outdoor enclosure and into their big winter quarters inside the house. A look behind the scenes with the real Business Guinea Pigs.

New in the series · October 6, 2026

Volume 6 is here: Rocky Buys a Share

Rocky splits the old lemonade stand into twenty cards and sells nineteen of them. What a share is, how a share price gets set and why co-owner doesn't mean boss. For kids 10 and up.

Printables · October 4, 2026

Advent coloring calendar

24 doors plus two extras to color, starring the Business Guinea Pigs. A German-language PDF for €4.90 in the FLITCH shop and on Etsy.

All the news

The Four

Four guinea pigs, four opinions

Because they see the same situation from completely different angles, money and business become something you can actually get your head around. Here they introduce themselves with the line from their profile.

All the characters in the series

The Books

Six volumes. Each one explains one big topic.

Each volume tells an everyday story and can be read on its own. Every paragraph is in German with the English right below it, so kids can read in English and pick up some German along the way.

All six volumes

Yes, they're real

Not made up. Just written a little chattier.

Rocky, Mr. Grey, Toffy and Mojito aren't made-up mascots. They really live with us. In summer they're outside in their big outdoor enclosure; in the cold months they move into their quiet winter quarters inside the house. In the books they talk a bit more than in real life. Usually.

Photo: Rocky, the real guinea pig
Rocky Picked by our son. He looks like a little rock star.
Photo: Mr. Grey, the real guinea pig
Mr. Grey Wasn't supposed to come home with us at all. Then Christian spotted him, as gray as his name.
Photo: Toffy, the real guinea pig
Toffy Also our son's pick, warm and creamy like toffee candy.
Photo: Mojito, the real guinea pig
Mojito Daria's very own guinea pig, named after her favorite cocktail, even though he looks more like a piña colada.

Real & in the Books

FLITCH Club · free

Free pages to print

The FLITCH Club has free single pages to go with the books: the “My First Lemonade Stand” math worksheet from Volume 1, two coloring pages for Volume 1 (Rocky's big idea, Toffy's lemonade stand), a certificate and materials for parents who want to talk with their kids about money. Plus new little extras, added regularly. All you need is an email address; signing up is a job for the grown-ups.

Not part of the Club: the Business Guinea Pigs coloring book (€4.90), Die Schweinchenkasse, an allowance planner (€6.90), and the Advent coloring calendar (€4.90). They're German-language booklets you can buy in the FLITCH shop and on Etsy.

Toffy shows off his diversified portfolio: four carrot slices in four different spots

Which guinea pig says this?

One line, three suspects. Tap your pick.

1. Which guinea pig explains this? “Too cheap always smells like a catch.”

For parents and teachers

Reading along with a child?

Here you'll find ages, learning goals, the topics in each volume, sample pages and materials for school. The books are educational stories: simplified for kids, accurate on the facts, and not financial or legal advice.

Daria Helck, author of the Business Guinea Pigs
Daria Helck writes the books. The kids in the books are named after her and Christian, the founders of FLITCH.

The books are on Amazon; coloring books and extras are in the FLITCH shop and on Etsy.

Go to the FLITCH shop Books on Amazon FLITCH on Etsy