Unit Overview
Content Area: Math
Unit Title: Addition/Subtraction and the Number System
Unit: 1
Target Course/Grade Level: Third Grade
Timeline: Sept.-Nov.
Unit Summary: Students generalize their understanding of place value to 100,000, understanding the
relative size of numbers in each place. They apply their understanding of models for addition and
subtraction, place value, and properties of operations, in particular the commutative and the associative
properties, as they develop, discuss, and use efficient, accurate and generalize methods to compute sums
and differences of 2 and 3-digit numbers. Depending on the numbers and the context, they select and
accurately apply appropriate methods to estimate or mentally calculate sums and differences. Students
develop fluency with efficient procedures for adding and subtracting two and three digit numbers;
understand and explain why procedures work based on place value and properties of operations and use
them to solve problems.
Primary interdisciplinary connections: Language Arts
21st century themes and skills: Critical Thinking and Problem Solving, Communication and
Collaboration, Teamwork and Leadership, Creativity and Innovation
Standard 9.1: All students will demonstrate the creative, critical thinking, collaboration, and
problem solving skills needed to function successfully as both global citizens and workers in diverse
ethnic and organizational cultures.
Strand:
A. Critical Thinking and Problem Solving
Content Statement:
9.1.4.A: The ability to recognize a problem and apply critical thinking and problem
solving skills to solve the problem is a lifelong skill that develops over time.
Mathematical Practices:
3.MP.1 Make sense of problems and persevere in solving them.
3.MP.2 Reason abstractly and quantitatively.
3.MP.3 Construct viable arguments and critique the reasoning of others.
3.MP.4 Model with mathematics.
3.MP.5 Use appropriate tools strategically.
3.MP.6 Attend to precision.
3.MP.7 Look for and make use of structure.
3.MP.8 Look for and express regularity in repeated reasoning.
Learning Targets
Domain: Number and Operations in Base Ten
Cluster: Use place value understanding and properties of operations to perform multi-digit arithmetic.
Standard #
Standards
3.NBT.1
Use place value understanding to round whole numbers t the nearest 10 or 100.
3.NBT.2
Fluently add and subtract within 10000 using strategies and algorithms bases on place
value, properties of operations and/or the relationship between addition and subtraction.
CPI #
Cumulative Progress Indicator (CPI)
9.1.4.A.1
Recognize a problem and brainstorm ways to solve the problem individually or
collaboratively.
9.1.4.A.2
Evaluate available resources that can assist in solving problems.
9.1.4.A.3
Determine when the use of technology is appropriate to solve problems.
Unit Essential Questions
 How do you represent numbers?
 How does understanding place value help you
solve double digit addition and subtraction
problems?
 How do I recognize what strategy to use for a
specific problem?
 What strategies do I use to find the sums or
differences of whole numbers up to two and
three digits long?
 How do I take apart and recombine numbers in a
variety of ways for finding sums and
differences?
Unit Enduring Understandings
 The base ten numbers system is a “place value”
system.
 There is meaning attached to the quantity the
numerals of number represent.
 There is a relationship between 100s, 10s and 1s in
the base ten number system.
 Computational fluency involves the use of known
combinations to solve more difficult problems.
 Using mathematical tools helps to solve problems
and represent solutions.
 Two numbers added in either order yields the same
sum (commutative property).
 Three numbers added together can be regrouped
without changing the order and will yield the same
sum (associative property).
 There are a variety of strategies to solve addition
and subtraction problems.
Unit Learning Targets
Students will ...
 Identify the position of a digit in a number and how it affects rounding to the nearest 10 or 100.
 Students learn when, why and how to round numbers to the nearest 10 or 100.
 Read, write and sequence numbers to 1000.
 Represent a structure of 3 digit numbers as being composed of 100s, 10s and 1s.
 Solve addition and subtraction problems with 2 and 3 digit numbers by breaking numbers apart and
recombining them (algorithms).
 Add mentally by using compensation with multiple of ten.
 Use tens to subtract mentally
 Counting on to subtract mentally.
 Students apply commutative and associative properties to fluently add and subtract within 1,000.
 Write number sentences for word problems.
Evidence of Learning
Summative Assessment:
 Round to the nearest 10 and to the nearest 100 up to 1,000.
 Solve addition word problems by using algorithms.
 Demonstrate automaticity in all addition and subtraction facts.
 Find sums and difference of numbers up to 1,000 using strategies (pictures, algorithms, number lines,
numbers).
 Role play human number line to sequence large numbers (3 and 4-digit numbers).
 Role play digits in proper sequence of 4-digit numbers.
Equipment needed: Base 10 blocks, graph paper to align columns of numbers, place value mats
Teacher Instructional Resources: Scott Foresman Mathematics, Addison Wesley, and Marilyn Burns
Resource Guides
Formative Assessments
 Diagnostic checkpoints
 Student workbook
 Skill sheets
 Play games
 Skip count by 10’s, 100’s, 1,000’s
 Work with base 10 blocks and other manipulatives
Integration of Technology:
SMARTboard to play online games and utilize online resources.
Etools for digital place value blocks
Technology Resources:
Click the links below to access additional resources used to design this unit:
 www.pearsonsuccessnet.com
 www.http:lleduction.jlab.org/placevalue - Place Value Game with differentiation
 http://www.learningbox.com/base10/baseten.html - Base Ten Blocks
 www.janbrett.com/piggybacks/rounding.htm#quiz – The Seashell Rounding Activity Page
 www.dosity.com/2008/addsub/mystery10.htm - Read 3-digit #’s
 www.aaastudy.com/g31e_pxl.htm - Place Value Games
Opportunities for Differentiation:
Modifications: Provide graph paper to align numbers when computing. Provide Base 10 block to
compute.
Enrichment: Construct the missing digits in addends, subtrahends and minuends.
Teacher Notes:
Use equivalencies among pennies, dimes and dollars.
Read, write and sequence numbers to 1000.