Which one doesn't belong? Playing with shapes by Christopher Danielson

This is one shape book that will both challenge readers’ thinking and encourage them to think outside the box. Kirkus Star review

I do love to browse the non fiction shelves in the library I visit each week - I always find so many quirky books.  If I was using this book with a class I would copy each page to display - one per week over a term and then invite the children to talk about their 'answers'. Actually the author explains there are no 'right' answers here - you just need to be able to justify your ideas.

This brightly coloured book has four shapes on each page with the question - which one doesn't belong. This book was published in 2019 but it is still available in paperback for a good price. 

Bookseller blurb: Written by a celebrated math educator, this innovative inquiry encourages critical thinking and sparks memorable mathematical conversations. Children and their parents answer the same question about each set of four shapes- "Which one doesn't belong?" There's no one right answer--the important thing is to have a reason why. Kids might describe the shapes as squished, smooshed, dented, or even goofy. But when they justify their thinking, they're talking math! Winner of the Mathical Book Prize for books that inspire children to see math all around them.

There is also a version of this book available with a teachers guide:

In the companion teacher's guide, (9781625310811) Danielson shows how to facilitate rich discussions and teach mathematical argumentation using Which One Doesn't Belong? He models how to listen closely and respectfully to students' ideas about shapes. Danielson synthesizes research about how children learn geometry, discusses the role of geometry in the mathematics curriculum, and gives plenty of practical advice about different ways to implement Which One Doesn't Belong? in classrooms.

Christopher Danielson has a PhD in Mathematics. Take a look at his webpage. He is clearly a very passionate educator. In this video (3 minutes) he talks about the inspiration for Which one doesn't belong? and as a bonus you can see inside the book. 

I am keen to look for this book too: