1. Addition and Subtraction Strategies
Unit of Study 13: Building Fluency with Addition and Subtraction
Global Concept Guide: 1 of 1

2. Content Development
Students have had ample opportunity to apply addition and subtraction strategies in a variety of problem solving scenarios.
According to the standard, MAFS.2.OA.2.2, students will FLUENTLY add and subtract within 20 using mental strategies. By the END of grade 2, know from MEMORY all the sums of two one-digit numbers.
Students have had ample opportunity to practice strategies, in this unit, they will be refining those strategies for quick recall of all the basic facts.
According to Van de Walle, “an efficient strategy is one that can be done mentally and quickly. The emphasis is on efficient. Counting is not efficient. If drill is undertaken when counting is the only strategy available, all you get is faster counting” (Van de Walle, 2006).
In this unit, students will also fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction (MAFS.2.NBT.2.5).
As you work with students throughout the unit, pay close attention to students who are struggling or need extension. Modify the plans as needed to ensure all students receive work that is appropriate for their learning.

3. H.O.T Questions for Unit Will any three numbers create a fact family?
Is there any math problem where using place value would not be a good strategy?
Can you use your knowledge of a ten frame to solve any addition and subtraction sentence?
How does an understanding of fact families help you build fact fluency?
Which strategy is most efficient and why?
Which strategy is least efficient and why?
Is it ever appropriate to use more than one strategy when solving problems?
How do you know which strategy to use?

4. Day 1
Essential Question: How can I use strategies to add and subtract two one-digit numbers?
Students can use strategies to build fluency by solving real-world problems or playing games:
Sample Games:
Number War- This is a two-player game. Each student gets a set of number cards with the digits Each player turns over two cards and finds the sum. The person with the greater sum earns a point. Play continues until one player reaches 10 points.
Read my Mind- This game involves 3 players. Player A and Player B each have a stack of digit cards with the digits 0-9. Each player selects a card and places it on his/her forehead. Player C calls out the sum of the two cards. Player A tries to guess their number because they can see Player B’s digit as well as they know the sum from Player C.
Sample Tasks:
Basic Fact Connections
Basic Fact Problems
Basic Fact Problems: Doubles
By the end of Day 1, students will be more efficient at solving basic facts.

5. Day 2
Essential Question: How can I use fact families to add and subtract two one-digit numbers?
The purpose of this day is for students to understand the inverse relationship between addition and subtraction to help them build their fact fluency.
Sample Game:
Fact Family Card Game:
Materials: Deck of cards with Jacks, Queens, Kings removed
Dealer distributes three cards to each student.
Each student looks at their cards to determine if the three cards can be arranged to make a Fact Family.
Each student shows their sets of cards and students discuss whether or not they have a fact family.
Lesson Ideas:
Fact Family Houses
Fact Family Problem Solving
Fact Family Problems
By the end of Day 2, students will be able to use fact families to efficiently solve problems fluently.

6. Day 3
Essential Question: How can I use strategies to add and subtract multi-digit numbers?
On day 3, students are extending their understanding of basic fact fluency to addition and subtraction with two-digit numbers within 100.
Sample Game:
Provide pairs of students a deck of cards with tens, jacks, queens, and kings removed. For the game, Aces are worth one.
Each player selects 4 cards to create two separate two-digit numbers.
Using the 4 digit cards, the student wants to create two two-digit numbers that, when combined, together have a sum LESS than 100.
The student that gets the closets to 100 WITHOUT going over earns a point.
Play continues until one player earns 10 points or time runs out.
Lesson Ideas
Solve Problems involving two-digit numbers
Problem Solving A Different Approach
Real World Problem Solving

7. Day 4
Essential Question: How can I use strategies to add and subtract multi-digit numbers?
On day 3, students extended their understanding of basic fact fluency to addition and subtraction with two-digit numbers within 100.
Sample Game:
Provide pairs of students a deck of cards with tens, jacks, queens, and kings removed. For the game, Aces are worth one.
Each player selects 4 cards to create two separate two-digit numbers.
Using the 4 digit cards, the student wants to create two two-digit numbers that, when combined, together have a sum LESS than 100.
The student that gets the closets to 100 WITHOUT going over earns a point.
Play continues until one player earns 10 points or time runs out.
Lesson Ideas
Solve More Problems involving two-digit numbers
Problem Solving Scenarios-Arcade
Mixed Review Word Problems
Critical Area Project-Building Fluency

8. Day 5
Essential Question: How can I use efficient strategies to add and subtract multi-digit numbers?
Day 5 focuses on students selecting efficient strategies to solve problems. Utilize any of the resources you have not used on the previous days to help your students fluently solve problems.
Lesson Ideas:
Mixed Review Word Problems
Fact Family Houses
Fact Family Problem Solving
Basic Fact Connections
Basic Fact Problems
Basic Fact Problems: Doubles
Solving Problems
Problem Solving A Different Approach
Fact Family Problems
Real World Problem Solving
Critical Area Project-Building Fluency
Today is an excellent day to administer the:Performance Task

9. Enrich/Intervention/Reteach
Reteach Task
Enrich