Lesson 9 give more on multiplying by two-digit numbers, and lesson 10 addresses multiplying greater numbers. In the lesson on one digit numbers, lesson 5, the topic is introduced by the statement, You can use basic facts to multiply by one-digit numbers . A problem situation is introduced. The example shows the standard algorithm with some explanatory notes. It also shows the same problem solved with mental math and makes reference to the Distributive property.
Students are to think and discuss the similarities of the two methods.
These are followed by an application problem requiring multiplication, another requiring estimation, and a journal idea. This lesson is followed by a problem-solving lesson and a Checkpoint that provides more practice on mental multiplication, estimating products, and multiplying. Then an Explore lesson presents partial products in an array context. Lesson 8 introduces multiplication by two-digit numbers in the context of partial products and multiples of 10. In each example, the solution using an array to represent the partial products and using the standard algorithm are presented.