## Unit 1: Addition and Subtraction of Whole Numbers

### What will your child learn in Unit 1?

In Unit 1, fourth graders will learn about place value understanding within 1,000,000. They will represent numbers in different ways, such as written form, standard form, and expanded form. Students will learn mental math strategies such as estimation and rounding. Furthermore, students will primarily solve addition and subtraction problems involving large numbers. Students will use a variety of strategies to solve the problem, however teachers will guide the students to use the standard algorithm. Students will understand why this method works and will apply this strategy to solve problems involving larger numbers efficiently. Children go through different phases to quickly and accurately solve multi-digit addition and subtraction problems. In third grade, students were primarily in phase 2 with a focus on invented strategies. In fourth grade, students will primarily be in phase 3 with a focus on the standard algorithm.

### What math strategies will your child use in Unit 1?

There are a variety of strategies that your child learned in second and third grade to solve multi-digit addition and subtraction problems besides the standard algorithm. The type of strategy depends on types of numbers used in the problem. The handout below gives an explanation of the different types of multi-digit addition and subtraction strategies.

Check out the videos below to see the math strategies in action. Most of the explanations are from students from our district. Thank you to the students for volunteering to explain their thinking!

### How can you support your child at home to reinforce the concepts taught in Unit 1?

There are several ways to have your child practice the math concepts at home. Try the following activities:

• Give your child an addition or subtraction problem and have them solve it mentally and explain their thinking verbally.
• Visit Base Blocks Subtraction to have your child practice the standard algorithm using place value blocks.
• Visit Thinking Blocks to have your child build models and solve addition and subtraction word problems.
• Play Make the Largest Sum to have your child practice adding numbers using the standard algorithm.
• Play Roll and Round to have your child practice rounding numbers to the nearest hundred.
• Play Comparing Digits to have your child practice comparing large numbers.
• Math Games for Home: Print the handouts to practice concepts through games.