What do textbooks say about Number and Operations Base Ten K-5?

Source:
An Analysis of Addition and Subtraction iWord Problems in American and Soviet Elementary Mathematics Textbooks by James Stigler, Karen C. Fuson, Mark Ham, and Myong Sook Kim

Four American textbooks resembled each other but differ from Soviet text series.
1) Destruction of word problemsacross the various problem types was uneven in American texts with two thirds of all problems being of only three simple one step types. Soviet problems were distributed over many types, including more complex two-step problems.
2) Most of the problems in the American texts are those that American children find easiest to solve.
3) Soviet textbooks also provide a more variable and a more distributed method of presentation than to the American textbooks.