In addition, thinking patterns based on place value are addressed. In this section, estimation and subtraction with zeros are emphasized to prevent errors and to work for efficiency. Strategies for mental computation precede the development of the skills of rounding to the nearest ten to estimate sums and differences when working with US currency. The lesson on properties and equations develops skills that are then applied in problem solving. Theis topic is presented early in the text so that application can be used in subsequent units.
Much emphasis is placed on students understanding the basic units of measure.
Both metric and customary units are taught as separate systems. Multiplying by tens, hundreds, and thousands, is essential for estimating products, for understanding the multiplication algorithm, and for mental computation. Multi-step problems that can use practical situations enable the student to visualize the action, determine the question, and obtain the information needed to solve the problem. This unit begins with work on factors and primes. The importance of place value and placement of digits in the quotient is stressed throughout activities dealing with money.