It is the "10-minute Block". It is fun. I am curently doing one for my niece for Xmas. For one niece, I made a quilt with the large "Twister" block and so I had 10" squares cut. I was going to make another one like that for my other niece and then I read about the "10 Minute Block" on here so I cut my 1-" sqaure into 4 sqaures and then uses a different coordinating 5" square with it. It is looking really nice so far. About 1/2 done making the blocks and came home early from work today to try to finish those blocks yet today--but here I am! --Addicted to this site! That's not all bad--that's how we learn about cool things like the "10 Minute Block"! By the way, I did not buy the book, I just used some sampel fabric to try it and then started with the quilt.