Grade 2: Chapter 4 –2-Digit Addition

Chapter Essential Questions:How do you use place value to add 2-digit numbers? What are some different ways to add 2-digit numbers?

Before
(Grade One) / Chapter Four Standards
Grade Two / After
(Grade Three)
Represent and solve problems involving addition and subtraction.
(1.OA.1, 1.OA.2)
Use place value understanding and properties of operations to add and subtract.
(1.NBT.4, 1.NBT.6) / Number & Operations in Base Ten 6:Add up to four two-digit numbers using strategies based on place value and properties of operations.
  • I can find a sum by breaking apart a 1-digit addend to make a 2-digit addend a multiple of 10.
  • I can use compensation to develop flexible thinking for 2-digit addition.
  • I can apply place-value concepts when using a break-apart strategy for 2-digit addition.
  • I can model 2-digit addition with regrouping.
  • I can draw quick pictures and record 2-digit addition using the standard algorithm.
  • I can record 2-digit addition using the standard algorithm.
  • I can find sums of three 2-digit numbers.
  • I can find sums of four 2-digit numbers.
/ Represent and solve problems involving multiplication and division.
(3.OA.3)
Use place value understanding and properties of operations to perform multi-digit arithmetic.
(3.NBT.2)
Number & Operations in Base Ten 9:Explain why addition and subtraction strategies work, using place value and the properties of operations.
  • I can model 2-digit addition with regrouping.

Number & Operations in Base Ten 5:Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
  • I can record 2-digit addition using the standard algorithm.
  • I can practice 2-digit addition with and without regrouping.
  • I can rewrite horizontal addition problems vertically in the standard algorithm format.

Operations & Algebraic Thinking 1: Use addition and subtraction within 100 to solve one- and two-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.
  • I can solve problems involving 2-digit addition using the strategy draw a diagram.
  • I can represent addition situations with number sentences using a symbol for the unknown number.

Each day the math block will begin with 15 minutes of Daily Math Review and Mental Math. The focus of DMR should be either prerequisite standard skills or previous chapter concepts that were not mastered. The focus of mental math should be based on the current Chapter’s skills and concepts. Adjust the amount of questions in DMR and MM to fit into the 15 minute time block.

Suggested Chapter Pacing

All lessons are paced for one day, unless otherwise indicated. Teachers may adjust to meet students’ needs.

Launching the Chapter / Pre-Assessment / Review Prerequisite Skills
Count on Me TE 233I
Model and Write TE 233I / Show What You Know Assessment
Identify Tier 2 and Tier 3 Groups for Small Group Instruction.
Day Before Lesson 4.1 / Vocabulary Activity
Concentration TE 236A / Vocabulary Builder
TE 235 - Identify students who will need further vocabulary support for Chapter Four. / Preview Chapter Centers
Introduce chapter games, activities, and literature students will be using during center time. / School – Home Letter
Read together and send home.
I Can Statement / Essential Question / Implementation Notes
Lesson 4.1
Numbers and Operations in Base Ten 6 / I can find a sum by breaking apart a 1-digit addend to make a 2-digit addend a multiple of 10. / How does breaking apart a number make it easier to add? /
  • Base-Ten Blocks
  • Introduce Game: 2-Digit Shuffle
  • Introduce Literature: Nature’s Numbers
  • Students could break up a problem in multiple ways depending on strategy choice: 27 + 8 = 27 + 3 + 5 or 27 + 8 = 20 + (7 + 8).

Lesson 4.2
Numbers and Operations in Base Ten 6 / I can use compensation to develop flexible thinking for 2-digit addition. / How can you make an addend a ten to help solve an addition problem? /
  • Introduce Activity: Cool Blades
  • Students could break up a problem in multiple ways depending on strategy choice: 27 +38 = 25 + 40 or 27 + 38 = 20 + 30 + (7 + 8).

Lesson 4.3
Numbers and Operations in Base Ten 6 / I can apply place-value concepts when using a break-apart strategy for 2-digit addition. / How do you break apart addends to add tens and then add ones? /
  • Students could break up a problem in multiple ways depending on strategy choice: 27 +38 = 25 + 40 or 27 + 38 = 20 + 30 + (7 + 8).

Lesson 4.4
Numbers and Operations in Base Ten 6
Numbers and Operations in Base Ten 9 / I can model 2-digit addition with regrouping. / When do you regroup in addition? /
  • Base-Ten Blocks
  • Introduce Activity: Pebble Beach
  • It is not mathematically incorrect to refer to a place value drawing of 62 as 5 tens and 12 ones.

Lesson 4.5
Numbers and Operations in Base Ten 6 / I can draw quick pictures and record 2-digit addition using the standard algorithm. / How do you record 2-digit addition? /
  • Base-Ten Blocks
  • Introduce Game: Soccer Sums
  • Students may continue to use strategies based in place value. Teachers need not feel obligated to move students to using a standard algorithm in second grade.

Lesson 4.6
Numbers and Operations in Base Ten 6 / I can record 2-digit addition using the standard algorithm. / How do you record the steps when adding 2-digit numbers? /
  • Introduce Activity: Marbelous
  • Introduce Literature: Butterfly Farm
  • Students may continue to use strategies based in place value. Teachers need not feel obligated to move students to using a standard algorithm in second grade.

Lesson 4.7
Numbers and Operations in Base Ten 5 / I can practice 2-digit addition with and without regrouping. / How do you record the steps when adding 2-digit numbers? /
  • Introduce Activity: All that Jazz
  • Introduce Activity: Butterfly Farm
  • Students may continue to use strategies based in place value. Teachers need not feel obligated to move students to using a standard algorithm in second grade.
  • Mid-Chapter Checkpoint is optional TE276

I Can Statement / Essential Question / Implementation Notes
Lesson 4.8
Numbers and Operations in Base Ten 5 / I can rewrite horizontal addition problems vertically in the standard algorithm format. / What are two different ways to write addition problems? /
  • Students may continue to use strategies based in place value. Teachers need not feel obligated to move students to using a standard algorithm in second grade.

Lesson 4.9
Operations and Algebraic Thinking 1 / I can solve problems involving 2-digit addition using the strategy draw a diagram. / How can drawing a diagram help when solving addition problems? /
  • Introduce Activity: Aqua Addition
  • Introduce Activity: School Store
  • Students may use a different equation to solve the story problems other than the one listed.
  • Students may use any strategy to solve the problems.

Lesson 4.10
Operations and Algebraic Thinking 1 / I can represent addition situations with number sentences using a symbol for the unknown number. / How do you write number sentence to represent a problem? /
  • Students may use a different equation to solve the story problems other than the one listed.
  • Students may use any strategy to solve the problems.

Lesson 4.11
Numbers and Operations in Base Ten 6 / I can find sums of three 2-digit numbers / What are some ways to add three numbers? /
  • Students may continue to use strategies based in place value. Teachers need not feel obligated to move students to using a standard algorithm in second grade.
  • Students may use any strategy to solve the problems.

Lesson 4.12
Numbers and Operations in Base Ten 6 / I can find sums of four 2-digit numbers. / What are some ways to add four numbers? /
  • Students may continue to use strategies based in place value. Teachers need not feel obligated to move students to using a standard algorithm in second grade.
  • Students may use any strategy to solve the problems.

Resources and Centers for Chapter 4
Technology / Hands-On Resources / Centers
Digital Lesson: Engage / MathBoard / Activity: Cool Blades
Fastt Math / Base-Ten Blocks / Activity: Pebble Beach
Interactive White Board Lesson / Math Journal / Activity: Marbelous
e Student Edition / Other Hands-On Resources may be needed for Small Group Instruction Activities. / Activity: All that Jazz
Mega Math / Activity: Aqua Addition
Animated Math Models / Activity: School Store
Math on the Spot Videos / Literature: Nature’s Numbers
iTools: Counters / Literature: Butterfly Farm
iTools: Base-Ten Blocks / Game: 2-Digit Shuffle
Personal Math Trainer / Game: Soccer Sums
Game: What is the Sum?
Additional Resources for Chapter 4
Number and Operations in Base Ten 9 / Number and Operations in Base Ten 5 / Operations in Algebraic Thinking 1
CGI – Addition and Subtraction Story Bank / Equations and Expressions Practice / Addition and Subtraction Puzzles
Mastering the Basic Facts in Addition and Subtraction: Chapter 2: Plus 1 and Plus 2
Mastering the Basic Facts in Addition and Subtraction: Chapter 3: Adding 0
Mastering the Basic Facts in Addition and Subtraction: Chapter 4: Adding 10
Mastering the Basic Facts in Addition and Subtraction: Chapter 5: Doubles
Mastering the Basic Facts in Addition and Subtraction: Chapter 6: Making 10
Mastering the Basic Facts in Addition and Subtraction: Chapter 7: Using 10s
Mastering the Basic Facts in Addition and Subtraction: Chapter 8: Using Doubles
2.NBT.5 : What does this standard mean the students will know and be able to do?
There are various strategies that Second Grade students understand and use when adding and subtracting within 100.
The standard algorithm of carrying or borrowing is neither an expectation nor a focus in Second Grade.
Adding and subtracting fluently refers to knowledge of procedures, knowledge of when and how to use them appropriately, and skill in performing them flexibly, accurately, and efficiently. Students should have experiences solving problems written both horizontally and vertically. They need to communicate their thinking and be able to justify their strategies both verbally and with paper and pencil.
Possible Strategies
Place Value Strategy
67 + 25 =
I broke both 67 and 25 into tens and ones. 6 tens plus 2 tens equals 8 tens. Then I added the ones. 7 ones plus 5 ones equals 12 ones. I then combined my tens and ones. 8 tens plus 12 ones. / Counting On and Decomposing a Number Line Leading to Ten
67 + 25 =
I wanted to start with 67 and then break 25 apart. I started with 67 and counted on to my next ten. 67 plus 3 gets me to
70. I then added 2 more to get to 72. I then added my 20 and got to 92. / Commutative Property
67 + 25 =
I broke 67 and 25 into tens and ones so I had to add 60+7+20+5. I added 60 and 20 first to get 80.
Then I added 7 to get 87. Then I added 5 more.
My answer is 92. / Relationship between Addition and Subtraction
63 – 32 =
I broke apart both 63 and 32 into tens and ones. I know that 2 plus 1 equals 3, so I have
1 left in the ones place. I know that 3 plus 3 equals 6, so I have a 3 in my tens place.
My answer has a 1 in the ones place and 3 in the tens place, so my answer is 31. / Other Possible Strategies:
  • Incremental adding
  • Compensation
  • Adding up
  • Incremental subtracting
  • Subtracting by place value
  • Associative Property
  • Identity Property of 0

2.NBT.6: What does this standard mean the students will know and be able to do?
This standard calls for students to add a string of two-digit numbers (up to four numbers) by applying place value strategies and properties of operations.
Students demonstrate addition strategies with up to four two-digit numbers either with or without regrouping. Problems may be written in a story problem format to help develop a stronger understanding of larger numbers and their values.
Example:
43 + 34 + 57 + 24 = ___
Student A
Associative Property
I saw the 43 and 57 and added them first, since I know 3 plus 7 equals 10.
When I added them 100 was my answer.
Then I added 34 and had 134. Then I added 24 and had 158. / Student B
Place Value Strategies
I broke up all of the numbers into tens and ones. First I added the tens.
40 + 30 + 50 + 20 = 140.
Then I added the ones. 3 + 4 + 7 + 4 =
18. Then I combined the tens and ones and had 158 as my answer. / Student C
Place Value + Associative Property
I broke up all the numbers into tens and ones. First I added up the tens.
40 + 30 + 50 + 20. I changed the order of the numbers to make adding easier. I
know that 30 plus 20 equals 50 and 50 more equals 100. Then I added the 40 and got 140. / Student D
Then I added up the ones. 3 + 4 + 7 +
4. I changed the order of the numbers to make adding easier. I know that 3 plus 7 equals 10 and 4 plus 4 equals 8.
10 plus 8 equals 18. I then combined my tens and my ones. 140 plus 18 equals 158.

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Grade 2 – Chapter 4