of Grandmother Fish & Clades

June 21, 2022
by Jonathan Tweet
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Since 2015, we have been creating imaginative ways for kids to learn about science, especially evolution. We are all related!

Grandmother Fish: A Child’s First Book of Evolution
Groundbreaking and delightful. Available from Macmillan through any bookstore. Ask for it at an independent bookstore near you (find a store). Hoot! Hoot! Learn more.

Clades & Clades Prehistoric
Animal-matching card games that teach evolutionary relationships among animals—including humans! A “clade” is any complete branch of the evolutionary family tree. Available direct from Atlas Games or ask for it at your friendly local game store. Learn more.

A “cladogram” of all the animals in Clades

Clades Solo
This app provides a one-player Clades experience—with dinosaurs. Learn more.

Crow Scientist
With this free app, kids learn to observe crows the way scientists do. Designed with crow scientists John & Colleen Marzluff. Learn more.

Planet Voyagers
This beautiful board game teaches kids about the solar system and Earth’s place in it. Available direct from SimplyFun.

September 11, 2023
by Jonathan Tweet
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Grandmother Fish’s Eureka Moment

Ten years ago, after I got back from Burning Man 2013, I had a eureka moment and realized how I could make my kids’ book really work. This was just after I was squeezed out of my last corporate job, doing game design at Amazon. At this point, I had been working on Grandmother Fish for almost 15 years, and in fact I had stalled on it. With Grandmother Fish on hold, my then-current project was a book about the historical Jesus and the ways that we are living in a world that he made. 

As it happened, I was soaking in my hot tub in a highly relaxed state, thinking about the earliest sorts of language. I had been reading The Symbolic Species by Terence Deacon, which lays out how language might have developed (unconvincingly, I might say). It occurred to me that in primeval times a wise elder might have mimcked the actions of an animal in order to convey information about it, and then it hit me that in Grandmother Fish the kids should mimic the “grandmothers.” I shook all over, and I knew that I had the secret of getting the book to work, only better than I’d originally imagined. 

Up until this point, the book had called the child’s attention to anatomy, such as “Great-Great-Great-Grandma Fish had bones.” With the switch from nouns to verbs, “bones” got changed into “wiggling” and “chomping.” Verbs are better than nouns: they’re more fun, they engage preverbal kids better, and they’re more memorable. A mother of two autistic kids tells me that Grandmother Fish a great book for them.

Here are some early notes that I wrote as I struggled to frame the big ideas in Grandmother Fish. 

April 6, 2023
by Jonathan Tweet
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Clades Solo Updated & Free

A new, free version of the Clades Solo app is now available on Apple, Android, and Amazon. Match animals by their evolutionary histories and see how fast you can play through the deck! The new version adds the standard 12-card version to the existing 9-card game. (I like playing the 12-card game on easy mode because it’s fast.) Play with the basic Clades cards, with the Clades Prehistoric cards, or with a mix of them. Clades Solo feature’s Karen’s lovely art and plenty of science notes for players who love biology and evolution. The app is now free, so tell the teachers, scientists, and animal-lovers you know about it. Check it out! 

June 27, 2022
by Jonathan Tweet
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Crow Scientist in Persian

Crow Scientist is now available in Persian (Farsi)! In March, Nasser Yousefi of DONYA  Children’s Research Institute contacted Dr Marzluff about translating our app into Persian. The institute works on early childhood education and development in Iran. They have been working on a children’s crow project for some time, drawing kids’ attention to the lives of crows. Everyone loves crows! Now they have our app to help them with their valuable educational work. We hope that in this small way, our the shared love of children, education, and crows builds a connection between American and Iranian citizens.

Our developer, David Marques, would be happy to incorporate other languages into the app if others can provide the translated text. Which language will be next?

Crow Scientist teaches kids to observe crows the way a scientist does. Here in Seattle, you can hear young crows begging for food, so it’s a great time to show kids how to spot them. Learn more. Crow Scientist is free and ad-free! Get it here.

April 7, 2021
by Jonathan Tweet
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Planet Voyagers Released

Planet Voyagers from SimplyFun

My new game Planet Voyagers engages players with its planet discs, which show the planets in scale to each other (full-size images on the reverse). Players play cards at the same time, so there’s no waiting for your turn. Special cards reference the statistics for the individual planets, such as length of the year or components of the atmosphere. Score points by moving down the row, by winning the research tokens associated with the planets, and by playing special cards.

The game comes from SimplyFun, which has created a beautiful game set based on my black-and-white prototype.


Outside the US, you can order Planet Voyager though MyUS.com.

October 6, 2020
by Jonathan Tweet
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“Crow Scientist” is Live!

“Crow Scientist” is live on the iOS App Store, on Google Play, and on Amazon. Karen’s art is ready to go, and she’s taking some extra time to make sure we position the art the best way we can. An update in the near future will add the art. We could also use a couple 5-star reviews, if you’re so inclined.

We are still looking for people to give us feedback to improve the app. Get links and provide feedback on the publisher’s Crow Scientist page…


You can follow Colleen, the “Lead Crow Scientist”, on Instagram.



September 11, 2020
by Jonathan Tweet
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Beta Test the “Crow Scientist” App

We closed out our successful Kickstarter campaign two days ago, and our free app “Crow Scientist” is now in a public beta test. For this project, I worked with two crow scientists, John & Colleen Marzluff, and it’s turning out great. The programmer, David Marques, has a web page with links to the beta test for Apple and Android, as well as for submitting feedback, art, and photographs.

“Crow Scientist” App

You can also see more of “Crow Scientist” on Grandmother Fish’s Facebook page.

Grandmother Fish

Thanks for supporting evolution science for children.

June 14, 2019
by Jonathan Tweet
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Clades Solo with Dinosaurs

Karen and I have updated our mobile game, Clades Solo, with dinosaurs and better science notes. Now the app includes the extinct animals from the Clades Prehistoric tabletop card game. Play with either set of cards, or mix them together.

iTunes: https://itunes.apple.com/us/app/clades-solo/id1450055203

Google Play: https://play.google.com/store/apps/details?id=org.ideategames.CladesSolo

Amazon Kindle Fire: https://www.amazon.com/gp/product/B07NJG8KSY

Which two cards complete the triple with the dinosaurs?

Karen and I don’t have an advertising budget, so if you like Clades Solo, please tell a friend, a parent, or a teacher. Thanks.

January 30, 2019
by Jonathan Tweet
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Clades Solo Mobile App

A fast version of Clades for iOS and Android. Updated with dinosaurs, pterosaurs, and other prehistoric animals—play more science notes about the animals pictured in the game.

September 21, 2018
by Jonathan Tweet
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Grandmother Images for Teachers

When teachers present Grandmother Fish to classrooms, it’s handy to have images of the five Grandmothers. Here are full-size images of the Grandmothers, each to be printed on a letter-size sheet of paper. Sometimes for a reading I have five different kids volunteer to act out the sounds and motions of one Grandmother each. In that case, each kid can hold the image of their Grandmother for the class to see. When I do timeline exercises, again I get five kids to volunteer to stand up and show everyone where on the timeline their Grandmothers lived. Now that I have these images, each kid will get one to hold.

Click on an image to get the full-size PDF.

From GRANDMOTHER FISH: A CHILD’S FIRST BOOK OF EVOLUTION. Illustrations © 2016 by Karen Lewis. Reprinted by permission from Feiwel & Friends. All Rights Reserved.

If you use these images in a classroom, Karen and I would love to hear about it. Enjoy!