Module 5
Addition and Subtraction of Numbers to
1000 with Word Problems to 100

Overview

Throughout this module, students will:
• add and subtract within 1000.
• understand that when adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, and ones and ones.
• understand that sometimes when adding or subtracting it is necessary to compose or decompose tens or hundreds.
• mentally add and subtract 10 or 100 to a number (ex. 456 +10, 721-100)
• explain why addition and subtraction strategies work, using place value and the properties of operations.
Vocabulary
 Terminology Definition Illustration Algorithm A step-by-step procedure to solve a particular type of problem. 34 + 57 _____________ Compensation A strategy that involves adjusting one number to a tens number and then adjusting the other number to keep a balance. Compose To make 1 larger unit from 10 smaller ones. (ex.  1 ten for 10 ones) Decompose To break 1 larger unit into 10 smaller units.  (ex. 10 tens from 1 hundred)  Also referred to as "unbundling" or "borrowing". New Groups Below A strategy to show newly composed units on the line below the addition algorithm (can be shown working left to right or right to left) Simplifying Strategy A strategy to make mental addition or subtraction easier. 299+7 could be thought of as 299+1 +6=300+6=306 Chip Model A pictorial strategy using place value to solve addition or subtraction. Associative Property of Addition Changing the grouping of 3 or more addends does not change the sum