Tweet Last spring when I was doing the Mathematical Mindsets book study, I wrote a lot about rich mathematical tasks that all students can access but that also keep going or growing for students who need more challenge. Since then, I have been on a quest to add more tasks like this to my repertoire and recently I cam across one that I just have to share with the world. I first heard about Yohaku in this month's issue of Teaching Children Mathematics. I was sitting in a waiting room while…