I always say when you see that old black-and-white footage of the rocket on the launch pad and it falls over and explodes, that’s because people had slide rules. Not having the decimal point is a real drawback. You want the decimal point, take it from me.
The “Dots and Boxes” approach to place value used in this part (and throughout this book) and the “pies per child” approach to fractions comes from James Tanton, and are used with his permission. See his development of these and other ideas at http://gdaymath.com/.