Don Cohen's book testifies to his love of math and kids. While other reviewers speak of how informative, diverse, and refreshing his book is, I want to make a few brief comments on materials required and what instruction for young children presumes. (1) Children will have to know about number lines, fractions-to-decimals, and will have to be curious. (2) This is definitely not a remedial book for the un-curious. (3) The methods in this book are really for small group tutorials. (4) This book requires that the teacher understand high school geometry and algebra. (5) It is very helpful to have graphing calculators or a computer that kids can use to write programs in BASIC. (6) Students will learn about (in no particular order) topics in measurement, number theory and number patterns, algebraic thinking, geometric reasoning, and a little bit about graph theory. These materials are not simply about calculus.
Some of the more powerful things that children will learn are: (1) indexing of numbers; (2) fractions; (3) programming in BASIC; (4) iteration; (5) exponents, and e; (6) ratios (such as t he golden ratio, etc.). I had the hardest time with (7) continuing fractions, which are rarely taught these days and which, to me, are not intuitive.
Perhaps the word "intuitive" sums up Cohen's approach: his skills at math are sufficient enough that he can see connections and help youngsters intuit connections, which are then their "discoveries." He does not mind youngsters making mistakes, and he believes in constructionist math.
I used Cohen's materials in a summer program with first graders, to solve Zero's Paradox, which, in calculus terms is: What is the limit of the sum of (1/2)^nth power? It took five weeks of daily discussion to help them learn about fractions, adding fractions, fractions less than one, graphing the sum, and understanding the idea of when "close enough" is a "good enough" limit. We had a great time and the youngsters enjoyed the project.