Demonstrate fluency with addition and subtraction, within 100, by:
Flexibly using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
Comparing addition and subtraction strategies, and explaining why they work.
Selecting an appropriate strategy in order to efficiently compute sums and differences.
Step 1: Lesson Standards & Learning Goals
NOTE: The U.S. Standard algorithm is not expected until Grade 4 and should not be introduced in second grade. Students who have independently demonstrated proficiency with the strategies mentioned here should spend time working on adding and subtracting with expanded form which is the expectation in third grade.
Flexibly using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
Strategies based on place value
use base ten blocks or draw pictures of base ten blocks to solve problems
add tens and ones separately (on a number line, a hundreds board (hundreds chart), or as equations)
Properties of operations
use the commutative property to change the order of multiple addends or decomposed addends to find sums
Relationship between addition and subtraction
rewrite a subtraction problem as an addition problem (Result Unknown, Change Unknown, and Start Unknown)
Comparing addition and subtraction strategies, and explaining why they work.
examine two different strategies for the same problem
explain similarities and differences between the strategies (may use manipulatives (base ten blocks), drawings or equations to support their explanations)
explain why those strategies work (may use manipulatives (base ten blocks), drawings or equations to support their explanations)
Selecting an appropriate strategy in order to efficiently compute sums and differences.
select an appropriate strategy to find the answer
NOTE: "Efficient strategies" can be discussed when comparing approaches.
Why is place value important when adding and subtracting?
Which strategy is best for solving this problem?
How does the relationship between addition and subtraction help me become more fluent in problem solving?
What is the commutative property and how does it help with addition problems?
add
addends
base 10
commutative property
decompose
difference
differences
digit
fact family
ones
place value
relationship
similarities
strategy
subtract
sum
tens
Use strategies based on place value, properties of operations, and the relationship between addition and subtraction
Compare addition and subtraction strategies.
Explain why addition or subtraction strategies work.
Select an appropriate strategy to efficiently solve addition and subtraction problems.
Changing the order of the addends does not affect the sum.
Drawings or objects can be used to help to explain why addition and subtraction strategies work.
Addition and subtraction are inverse (opposite) operations.
There are multiple strategies to solve a problem.
Efficiently means to use the least amount of time.
Step 2: Assessment
NC.2.NBT.5 - CO - Howell - Sept. 15, 2023
NC.2 - Cluster 2 Review - CO - Howell - Jan. 23, 2023
NCDPI Assessments
Grade 2 Math Assessment Practice Prompts
Step 3: Lesson Instructions
Video Clip
Exploration
Show an addition and/or subtraction problem.
Have students use base 10 blocks (physical or interactive) to try to solve.
Tools 4 NC Teachers
Cluster 2 Lessons
Cluster 2 Math Routines Presentation
Cluster 2 Addition and Subtraction Anchor Charts
Math Expressions - (Barnes and Hearne) - Standards Alignment
Motivation Math
Think Up! Math
Khan Academy - 2nd Grade Math
Eureka Math/Engage NY Free Resources
Embarc Online (Eureka Math) -
Zearn Math - Online Support Practice for Eureka Math (Requires free account)
North Carolina Collaborative for Mathematics Learning - Grade 2 Instructional Framework
NCDPI Resources
Grade 2 Math Assessment Practice Prompts
Grade 2 Released Summative Assessments
