Elementary Mathematics

3rd Grade Unit 8 Overview and Standards

Use these links to access resources for this unit.

 Before You Begin this Unit…

Unit at a Glance 

Unit 8 is the third unit in Grade 3 focused on addition and subtraction skills. By the end of this unit students should be able to demonstrate sound understanding of 3.NBT.2 – adding and subtracting within 1000.

Your data from students’ performance in Units 1 and 3 will provide insight into your students’ specific needs. If students are still struggling with addition and subtraction combinations within 10, you may want to assess the combinations they know using the Hiding Assessment.

This unit builds upon the work of Units 1 and 3, as it extends students’ work with addition and subtraction with 3-digit numbers. There continues to be a very intentional application of the base ten system as students will have opportunities to use expanded form and other place value strategies.

Please remember that the standard algorithm is not introduced in 3rd grade as it can hinder place value understanding when introduced too early.

Read more here in this article.

Suggested Dates:
March 23-April 28

Estimated Duration:
21 days

*Investigation 1: 5  lessons 
*Investigation 2: 
5 lessons 
*Investigation 3: 
3 lessons (Exclude sessions 3.4, 3.5, 3.7, 3.8, and 3.9)

 Standards Addressed in the Unit

3.OA.8 Solve two-step word problems using the four operations. Represent these problems using equations with a letter standing for the unknown quantity. Assess the reasonableness of answers using mental computation and estimation strategies including rounding.

Identify arithmetic patterns (including patterns in the addition table or multiplication table), and explain them using properties of operations.

Fluently add and subtract within 1000 using strategies and algorithms based on place value, properties of operations, and/or the relationship between addition and subtraction.

  Use place value understanding to round numbers to the nearest 10 and 100.

  Rounding numbers to the nearest hundred.

Link to CCSS Unpacking Document-Updated Sept. '15