First Grade Curriculum
Chapter 13 - Addition and Subtraction to 40
Children learned the basic addition and subtraction facts of numbers to 20 through a variety of strategies such as part-part-whole, counting on, related facts, doubles, and properties in Chapters 3, 4, and 8. Children learned about the place value of numbers to 40 in Chapter 12. With this foundation of addition and subtraction and the knowledge of numbers to 40, children progress in this chapter to the standard vertical form for addition and subtraction of numbers to 40.
In this chapter, children are taught vertical form based on place value that can be used to add or subtract numbers without and with regrouping. In teaching children to regroup, they are encouraged to use place-value charts to correctly align the digits and to record the regrouping process. The frequent use of place-value charts in this chapter leads children away from a dependence on concrete representations which are not feasible when dealing with larger numbers in Chapter 17 and in later grades. Children are also reminded that addition can be used to check subtraction.
Children develop their addition skills further by learning to apply the Associate Property of Addition and number bonds in adding three 1-digit numbers using the strategy of making a 10.
Lastly, the learning of addition and subtraction without and with regrouping is applied to real-world problems. For a start children may still use manipulatives for assistance. They should, however, gradually be able to work out the problems without the use of manipulatives, such as as connecting cubes and base-ten blocks, and instead use place-value charts.
Articles and helpful tips to help your child with math: