Grade 02
Unit 06: Addition and Subtraction with Algorithms
5E Lesson Plan Math
Grade Level: 2nd grade
Subject Area: Math
Lesson Title: Unit 6 Addition and
Lesson Length: 15 days
Subtraction with Algorithms
THE TEACHING PROCESS
Lesson Overview
This unit bundles student expectations that address generating, representing and
solving addition and subtraction problem situations using algorithms, including the
standard algorithm, and recalling basic facts. Problems include situations related to
calculating savings over time. According to the Texas Education Agency, mathematical
process standards including application, a problem-solving model, tools and techniques,
communication, representations, relationships, and justifications should be integrated
(when applicable) with content knowledge and skills so that students are prepared to
use mathematics in everyday life, society, and the workplace.
Prior to this unit, in Unit 03, students recalled basic facts and applied strategies and
properties of operations based on place value to add up to four two-digit numbers or
subtract two-digit numbers without algorithms. Students explored flexible methods and
models to solve and represent addition and subtraction situations within 1,000, including
mental math, concrete models, pictorial representations, number sentences, and open
number lines.
During this unit, students apply strategies based on place value and properties of
operations to add up to four two-digit numbers or subtract two-digit numbers within
1,000 in real-world problem situations that include calculating how money saved
accumulates over time with deposits and withdrawals. Addition and subtraction
situations, where the unknown may be any one of the terms in the problem, should
include numbers that require regrouping to solve the problem. Students make
connections between representing and solving addition and subtractions problems
using flexible methods, concrete and pictorial models, and number sentences to mental
strategies and algorithms based on knowledge of place value and properties of
operations. Students generate and solve problem situations for a given number
sentence involving addition and subtraction of whole numbers within 1,000. Students
continue to apply basic addition and subtraction fact strategies to solve problems while
working toward automatic recall and fact fluency, thus increasing efficiency with mental
and algorithmic problem solving.
After this unit, in Grade 3, students will solve one- and two-step addition and subtraction
problems fluently using a variety of strategies based on place value and properties of
operations. Students will also use the estimation strategies of rounding and compatible
numbers to justify the reasonableness of their solutions.
In Grade 2, generating, representing, and solving addition and subtraction situations,
and recalling basic facts are subsumed within the Grade 2 Texas Response to
Curriculum Focal Points (TxRCFP): Using place value and properties of operations to
solve problems involving addition and subtraction of whole numbers within 1,000.
Calculating savings over time and distinguishing between a deposit and a withdrawal
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
are identified within the Grade 2 Texas Response to Curriculum Focal Points
(TxRCFP): Financial Literacy.
Unit Objectives:
Students will…
 Generate, represent, and solve addition and subtraction problem situations using
algorithms, including the standard algorithm, and recalling basic facts.
 Apply strategies based on place value and properties of operations to add up to
four two-digit numbers or subtract two-digit numbers within 1,000 in real-world
problem situations that include calculating how money saved accumulates over
time with deposits and withdrawals.
 Represent addition and subtraction problems using flexible methods, concrete
and pictorial models, and number sentences to mental strategies and algorithms
based on knowledge of place value and properties of operations.
 Work toward automatic recall and fact fluency, thus increasing efficiency with
mental and algorithmic problem solving.
Standards addressed:
TEKS:
2.1A- Apply mathematics to problems arising in everyday life, society, and the
workplace.
2.1B- Use a problem-solving model that incorporates analyzing given information,
formulating a plan or strategy, determining a solution, justifying the solution, and
evaluating the problem-solving process and the reasonableness of the solution.
2.1C-Select tools, including real objects, manipulatives, paper and pencil, and
technology as appropriate, and techniques, including mental math, estimation, and
number sense as appropriate, to solve problems.
2.1D-Communicate mathematical ideas, reasoning, and their implications using multiple
representations, including symbols, diagrams,graphs, and language as appropriate.
2.1E-Create and use representations to organize, record, and communicate
mathematical ideas.
2.1F-Analyze mathematical relationships to connect and communicate mathematical
ideas.
2.1G-Display, explain, and justify mathematical ideas and arguments using precise
mathematical language in written or oral communication.
2.4A-Recall basic facts to add and subtract within 20 with automaticity.
2.4B-Add up to four two-digit numbers and subtract two-digit numbers using mental
strategies and algorithms based on knowledge of place value and properties of
operations.
2.4C-Solve one-step and multi-step word problems involving addition and subtraction
within 1,000 using a variety of strategies based on place value, including algorithms.
2.4D-Generate and solve problem situations for a given mathematical number sentence
involving addition and subtraction of whole numbers within 1,000.
2.7C-Represent and solve addition and subtraction word problems where unknowns
may be any one of the terms in the problem.
2.11A-Calculate how money saved can accumulate into a larger amount over time.
2.11C-Distinguish between a deposit and a withdrawal.
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Unit 06: Addition and Subtraction with Algorithms
ELPS:
ELPS.c.1A-use prior knowledge and experiences to understand meanings in English
ELPS.c.2D-monitor understanding of spoken language during classroom instruction
and interactions and seek clarification as needed
ELPS.c.3C-speak using a variety of grammatical structures, sentence lengths,
sentence types, and connecting words with increasing accuracy and ease as more
English is acquired
ELPS.c.3D-speak using grade-level content area vocabulary in context to internalize
new English words and build academic language proficiency
ELPS.c.3H-narrate, describe, and explain with increasing specificity and detail as more
English is acquired
ELPS.c.5B-write using newly acquired basic vocabulary and content-based grade-level
vocabulary
ELPS.c.5F-write using a variety of grade-appropriate sentence lengths, patterns, and
connecting words to combine phrases, clauses, and sentences in increasingly accurate
ways as more English is acquired
Misconceptions:
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Some students may think they must add or subtract in the order that the numbers
are presented in the problem, rather than performing the operation based on the
meaning and action(s) of the problem situation.
Some students may think subtraction is commutative, rather than recognizing the
minuend as the total amount and the subtrahend as the amount being subtracted
(e.g., 5 – 3 is not the same as 3 – 5, etc.).
Some students may think, when using the standard addition algorithm, they can
record the sum of the digits in each column regardless of the amount rather than
recognizing that amounts of 10 or more require regrouping since only a single
digit is recorded in each column.
Some students may think, when using the standard subtraction algorithm, they
can subtract the smaller digit from the larger digit regardless of the location rather
than recognizing that if the digit on the top (minuend) is larger than the digit on
the bottom (subtrahend) regrouping will be necessary prior to subtracting.
Underdeveloped Concepts:
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Some students may not recognize the difference between an addition situation
and a subtraction situation based on the context of the problem.
Some students may recognize the inverse relationship of addition and
subtraction in basic fact families but do not apply the same understanding to
multi-digit numbers (e.g., if 7 + 3 = 10 is the inverse of 10 – 3 = 7, then 17 + 13 =
26 is the inverse of 26 – 13 = 17).
Some students may interpret the equal sign to mean that an operation must be
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
performed on the numbers on one side and the result of this operation is
recorded on the other side of the equal sign, rather than understanding the equal
sign as representing equivalent values (e.g., 10 + 8 = 13 + 5).
Vocabulary:
Addend – a number being added or joined together with another number(s)
Automaticity – executing a basic fact with little or no conscious effort
Balance – the amount of money that is in a bank account after a deposit or
withdrawal
Compose numbers – to combine parts or smaller values to form a number
Counting (natural) numbers – the set of positive numbers that begins at one and
increases by increments of one each time {1, 2, 3, ..., n}
Decompose numbers – to break a number into parts or smaller values
Deposit – money put into an account
Difference – the remaining amount after the subtrahend has been subtracted
from the minuend
Digit – any numeral from 0 – 9
Equal sign – a mathematical symbol representing equivalence
Expression – a mathematical phrase, with no equal sign, that may contain a
number(s), an unknown(s), and/or an operator(s)
Fact families – related number sentences using the same set of numbers
Interest earned – money received for saving money in a bank account
Minuend – a number from which another number will be subtracted
Number sentence – a mathematical statement composed of numbers, and/or an
unknown(s), and/or an operator(s), and an equality or inequality symbol
Place value – the value of a digit as determined by its location in a number such
as ones, tens, hundreds, one thousands, etc.
Saving – setting aside money earned or received for future use
Subtrahend – a number to be subtracted from a minuend
Sum – the total when two or more addends are joined
Term – a number and/or an unknown in an expression separated by an operation
symbol(s)
Whole numbers – the set of counting (natural) numbers and zero {0, 1, 2, 3,
..., n}
Withdrawal – money taken out of an account
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Related Vocabulary:
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Addition
Algorithm
Bank account
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(checking/
saving account)
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Increase
Inverse operations
Mental strategies
Operator/operation
Partial
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Regrouping
Result unknown
Solution
Start unknown
Strategy
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
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Calculate
Change unknown
Comparison
problem
Decrease
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sums/differences
Part-part-whole
Properties of
operations
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Subtraction
Transaction
INSTRUCTIONAL SEQUENCE
Phase: Engage
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Materials:
1 deck of cards per 2 students
chart paper for Activity 3
chart paper for Activity 4
piggybank-digital or real
paper empty piggy bank (1 per
teacher)
coins
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Handouts:
Correct or Not Correct (1 per
student)
Day 1
Review and practice addition strategies for math facts through 20.
Activity 1:
Use the PowerPoint: Addition Fact Strategies to review addition strategies.
Activity 2:
Partner up the students to play Addition Battle. Give each partner group a deck of
playing cards. Tell them that the face cards are all worth ten and the aces are worth
one and the rest of the cards are worth the numbers they show.
Instructions for playing: The partners should sit facing each other, then one partner
should deal the cards out. They should put their stack of cards in front of them. To start
they should say, “flip” and both partners should flip one card each in the middle of them.
The first partner to say the sum correctly gets the match. They should have time to play
several times.
Option: The teacher can rotate the students, so they have a new partner each time
they play.
Explore/Explain
Activity 3:
The students will now use what they know about the addition facts to decide if a given
equation is correct or not correct. Then they must justify their decision in writing.
Work through the following problems:
1. Display the following equation on chart paper: 9=4+5
Have the students Turn and Talk to their neighbor by telling each other if the equation
is correct or not correct. Then tell each other which addition strategy they would use to
prove or justify their answer.
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
Ask:
*Is this equation correct or not correct? (correct)
*How can you prove your answer? (This is a double plus 1 equation 4+4=8
add one more and it makes 9 or a double minus 1 equation 5+5=10 minus 1
=9, other answers will vary)
2. Display the following equation: 16=9+6
Ask:
*Is this equation correct or not correct? (not correct)
*How can you prove your answer? (This is an adding 9 equation 9+1=10 and
10+6=16 minus 1 equals 15, other answers will vary.)
3. Distribute handout: Correct or Not Correct
4. Partner work: They should work with their partner to complete the page.
They should take turns working the equations.
5. When most are finished use the chart paper to record the Correct or Not
Correct equations and have individual students write the strategy they used
under the equations to check over the problems together.
Activity 4:
1. Show the students the empty piggybank.
Ask:
* Does anyone know what this is? (it is a piggybank)
* Can anyone tell us what it is used for? (to put money in, to save your money
in)
2. Turn and Talk with your neighbor about why someone would save money.
Tell your neighbor two reasons someone would save money.
3. On chart paper write the title: Reasons to Save Money. Record the examples
that the students came up with on the chart.
4. Discuss how a piggybank is like a savings account at a bank. When you put
money in it it’s called a deposit.
Ask:
* When you have a piggybank/saving account how do you know how much
money is in it? (you have to count it and/or keep a record of what is in it)
Tell the students that we are going to deposit money into the bank and add what we are
putting in money as we go.
*Remind them to use the addition strategies when adding the coin amounts.
5. Add a nickel to the bank and say “Sara is depositing a nickel to her savings
account/piggy bank.
Ask:
* What does deposit mean? (to put money in an account/piggy bank)
* How much money did Sara save by putting the nickel in the bank? (5 cents)
* What is the balance of her savings account? (5 cents)
6. Add a dime to the piggybank and say “Sara is depositing a dime into her
savings account/piggy bank.
Ask:
* If she puts a dime in the piggybank, what will the balance of her savings
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
account be? (15 cents)
7. Add 2 pennies to the piggybank and say “Sara is depositing 2 pennies into her
savings account/piggy bank.
Ask:
* How much money does Sara have in savings now? (17cents)
* What happens each time Sara adds money to her account/piggy bank? (the
balance increases, she has more money)
* Is the number 17 odd or even? (odd)
* Why is it odd? (The number 7 is odd because 6 is even and has partners, but
if you add one more to 6 and get seven it won’t have a partner.)
Take the coins out of the piggybank and start again putting different amounts in and
having the students add each time you put more in.
What’s the teacher doing?
 Leading discussion during Addition
Strategies PowerPoint.
 Putting students in groups.
 Monitoring card game groups.
 Recording information on the chart
paper.
What are the students doing?
 Participating in addition strategies
PowerPoint discussion.
 Working cooperatively in groups
 Added coin amounts.
Phase Engage
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Materials:
A deck of cards for every 4
students
1 Set of Number Cards 1-20
Empty Piggy Bank from Day 1
coins
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Handouts:
Multi-Step Recording Sheet
Day 2
Review and practice subtraction strategies for math facts and multi-step 1-digit
problems.
Engage
Activity 1:
Use the PowerPoint: Subtraction Fact Strategies to review subtraction strategies.
Activity 2:
Put the students in groups of 3 or 4 to play Subtraction War. Give each group a deck
of playing cards. Tell them that the face cards are all worth ten and the aces are worth
one and the rest of the cards are worth the numbers they show.
Instructions for playing: Each group should sit facing each other in a circle and
number themselves 1-4, then one student should deal the cards out. Each student
should put their stack of cards in front of them. To start they should say, “flip” and each
student in the group should flip two cards in the front of them. Each group member
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
should make a subtraction fact going in order by the numbers 1-4 from their two cards
and tell the difference. They should also tell the subtraction strategy that they used to
find the difference (doubles, doubles plus/minus 1, counting up, counting back, etc.).
Whichever group member has the highest difference gets everyone’s cards. And they
repeat the procedures again until the cards are all gone. They should have time to play
several times.
*If you put them in group of 4 each group member should get 13 cards. They will “flip” 6
different times and on the 7th time they will only have 1 card. Tell them to make a
subtraction fact using 0.
Activity 3:
Display a subtraction number sentence such as 13-9= ?
Have the students record the number sentence in their Math Journal. Then have the
students generate a problem situation about the number sentence.
Have different students share the problem situation they came up with.
Explore/Explain
Activity 4:
Review multi-step equations.
Distribute base ten blocks and a Multi-Step Recording Sheet to each student.
Display this Problem Situation:
Regina has 8 rings. She gives her best friend Beth 4 of her rings. For her
birthday she gets her 3 new rings from her mother. How many rings does Regina
have now?
Have the students read aloud the problem situation.
Turn and Talk: Have the students turn and talk to their neighbor about the actions
taking place in the problem. Tell them to name 2 actions that take place.
Ask:
* What two actions are taking place in this problem situation? (gives and
gets)
* What operation (addition/subtraction) does the action word gives stand for
in this problem situation? ( subtraction) How do You know?
* What operation (addition/subtraction) does the action word gets stand for
in this problem situation? (addition) How do You know?
Explain that in this problem situation there is more than one step to solve it. We will
need to start with the 8 rings she already has and subtract the 4 she gives away to get
the difference. Then take the difference and add the 3 new rings she gets.
* What would the number sentence be for this problem situation?
(8 – 4 + 3 =____)
Have the students record the multi-step number sentence on their recording sheet.
Tell them that they are going to use their place value blocks to solve the number
situation and record the steps on their recording sheet.
Ask:
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
* Which of the blocks are they are going to use? ones, tens, or hundreds? (ones)
Have the students show 8 ones. Have them draw 8 dots on the recording sheet.
* What is our next step? (to subtract the 4 rings she gives to her friend)
Have the students remove 4 of the ones. Have them cross out 4 dots on their recording
sheet.
* What is the difference? (4 ones)
* What part of the number sentence did we just work? (8-4=4)
Have the students record the number sentence on their recording sheet.
* Are we finished? Is this the answer to the problem situation? Why? (No,
we still have to add the 3 rings she gets from her mother.)
Have the students add 3 ones to the 4 they have showing. Have the students add 3
dots to the 4 they have showing on the recording sheet.
* How many ones do you have now? (7)
* What is the number sentence for what we worked? (3+4=7)
Have the students record the number sentence on their recording sheet.
Display the following problem situation:
Sherry has 9 colorful stickers on her notebook. Her friend attaches 6 more
stickers to Sherry’s notebook. Five of the stickers fall off. How many stickers are
on Sherry’s notebook?
Have the students read aloud the problem situation.
Turn and Talk: Have the students turn and talk to their neighbor about the actions
taking place in the problem. Tell them to name 2 actions that take place.
Ask:
* What two actions are taking place in this problem situation? (uses and
buys)
* What operation (addition/subtraction) does the action word attaches stand
for in this problem situation? (addition) How do You know?
* What operation (addition/subtraction) does the action word fall off stand
for in this problem situation? (subtraction) How do You know?
Explain that in this problem situation there is more than one step to solve it. We will
need to add 6 to 9 first and then use that sum and subtract 5 from it.
* What would the number sentence be for this problem situation?
(9 + 6 - 5 = ____)
Have the students record the multi-step number sentence on their recording sheet.
Tell them that they are going to use their place value blocks to solve the number
situation and record the steps on their recording sheet.
Ask:
* Which of the blocks are they are going to use? ones, tens, or hundreds?
(ones )
Have the students show 9 ones. Have them draw 9 dots on the recording sheet.
* What is our next step? (to add the 6 stickers that her friend attaches to her
notebook)
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
Have the students put 6 more ones with the 9 they already have. Have the students
draw 6 more dots on their recording sheet.
* What is the sum? ( 15 ones)
* What part of the number sentence did we just work? (9+6=15)
Have the students record the number sentence on their recording sheet.
* Are we finished? Is this the answer to the problem situation? Why? (No,
we still have to subtract the 5 stickers that fall off.)
Have the students remove 5 ones from the 15 they have showing. Have the students
mark out 5 of the dots they have showing on the recording sheet.
* How many ones do you have now? (10)
* What is the number sentence for what we worked? (15-5=10)
Have the students record the number sentence on their recording sheet.
Activity 5:
Display the empty piggybank from Day 1 with 2 nickels and a dime in it.
Ask:
* How much money does Felix have saved in his piggybank? (20 cents)
* If Felix takes out or withdraws a nickel, what will be the balance in the
bank? (15 cents)
Tell the students that when money is taken out of a bank or an account it is called a
withdrawal.
Ask:
* If Felix withdraws a dime from his bank, what is the balance in his savings
account/piggy bank? (5 cents)
* What operation is used when a withdrawal is made? (subtraction)
* What is happening to Felix’s money every time he makes a withdrawal? (His
savings is getting smaller, the amount is decreasing)
* Will he have enough money to buy a bike, if he only has a nickel in his
bank/account? (no, unless it costs 5 cents or less)
Continue putting coins in the empty piggybank and taking different amounts out. Have
the students subtract the amount being taken out each time.
What’s the teacher doing?
What are the student’s doing?
 Leading discussions
 Participating in discussions
 Putting students in groups.
 Working cooperatively in
Subtraction War card game
 Monitoring card game groups.
Phase: Engage
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Day 3
Materials:
chart paper
copy of Addition U.T.A. Anchor
Chart
base ten blocks or place value
discs
Math Journal (optional)
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Handouts:
Handout-Adding 2-Digit Numbers
Using Pictorial and the Algorithm
(1per student)
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
Two-digit addition using the traditional algorithm with base tens or place value
discs. Real world problem situations including, depositing money in a checking
account.
Engage
Activity 1:
This website: http://nlvm.usu.edu/en/nav/grade_g_1.html has a great tool Base
Blocks Addition that can be used along with the problems that are being worked in this
activity.
Create an Anchor Chart with the title:
1. Addition Using the Traditional Algorithm together with the class. (The
students can also record the anchor chart in the Math Journal)
2. Write the following number sentence on the chart paper: 39+44=_____
3. Discuss that a number sentence is written horizontally. Tell the students that
to add two numbers using the traditional algorithm the numbers are written
vertically.
Draw a place value chart showing tens and ones, then write the
numbers vertically making sure to emphasize lining up the digits ones place
and the digits in the tens place.
Tens
3
+ 4
Ones
9
4
Ask:
* What is the operation that we are using to solve this problem? (addition)
* If we are adding these numbers together how do we show that with our
base ten blocks? (we build both numbers)
Have the students build both numbers on their desk making sure to line up the
tens and the ones just like the numbers are lined up on the chart.
Remind the students that we read numbers from left to right and that’s how they
should build them on their desk.
Demonstrate on the anchor chart how the base ten blocks should be lined up like the
numbers.
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Unit 06: Addition and Subtraction with Algorithms
Tens
lll
llll
l
Tens
Ones
Ones
1
. . . . .
. . . .
+
. . . .
Tens
3
9
4
4
8
3
Ones
lll
.....
....
llll
....
6. Tell the students that the first step is to look in the ones place and add the
ones together.
Ask:
* How many ones are there, if you add 9+4? (13)
* Can we record 13 in the ones place? (No) Why? (The highest digit that
can go in the ones place is 9, anything above 9 is a 10 and has to go in the 10’s
place.)
Demonstrate on the pictorial counting ten ones, then circling the group of ten
and show it moving to the tens place.
Demonstrate on the place value chart recording 13 beside the chart then
write the 3 ones in the ones place and the 1 in the tens place above the 3 that is already
there.
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Tell the students that the second step is to add the tens place numbers together.
Demonstrate adding the digits in the tens place, then record the 8 in the ten’s
place.
Ask:
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Unit 06: Addition and Subtraction with Algorithms
* What is the sum of 39+44=____? (83)
Record the sum at the end of the number sentence.
Tell the students that the Anchor Chart we just made is for them to use to remind them
how to add two-digit numbers together using the traditional algorithm.
Activity 2:
Explore/Explain
1. Tell the students that the class will be working together to complete a two-digit
addition problem using base tens or place value discs to solve the problem.
The students should record information as the problem is worked. Remind
them they will be building the addition problem using base ten blocks and then
drawing pictorials to represent the numbers being added.
Distribute handout: Adding 2-Digit Numbers using Pictorial and the Algorithm and
work it together going step by step.
2. Partner Work: Tell the students that they are going to work two more addition
problem situations with a partner. Remind them that they can use the Anchor Chart
and/or the handout that we just completed together to help them complete the handout:
Addition Using the Traditional Algorithm.
3. Check over the handout together.
Activity 3:
Distribute handout: Money Earned From Chores.
Display the Empty Piggy Bank.
Read the scenario from the handout to the students. Discuss the chores Jerry is doing
and the money Jerry is paid and what he is saving.
Ask:
* When Jerry puts the money he has earned into his piggy bank or savings
account what is happening to the amount of money in his account?
(answers will vary; it is increasing, getting larger, he has more each time)
* Why is Jerry saving the money he earns? (To buy a kayak and for college)
* What are some other reasons that Jerry would save the money he earns?
(Answers may vary.)
As a whole class work the problem situations together. The teacher can project the
problems for the students to see or write them on the board or chart paper.
Remind the students that they are adding money, so they have to record a dollar sign in
front of each of the numbers they are adding and in front of the sum.
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Unit 06: Addition and Subtraction with Algorithms
What’s the teacher doing?
 Making the Anchor Chart
 Leading discussions
 Modeling the algorithm and pictorial
 Monitoring partner groups
What are the students doing?
 Listening to class discussions
 Participating in class discussions
 Recording the algorithms and
pictorials
 Working cooperatively with their
partners
Phase: Engage
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Materials:
base ten blocks
place value discs
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Handouts:
Story Problem Board and
Recording Sheet (1 per student
and teacher
Day 4
Two-digit addition with base tens and the traditional algorithm using the
traditional algorithm including generating a story for a given number sentence.
Activity 1:
1. Record the following two-digit numbers in a haphazard arrangement for the class to
see: 48, 22, 16, 37, 13, 54, 27, 36, 41, 25, 35, 40, 28, 43, 39.
2. Distribute a sheet of paper to each student. Instruct students to create 3 two-digit
addition problems that require regrouping (using any of the displayed numbers), and
record each problem and sum on the front side of their sheet of paper. Allow time for
students to complete the activity. Monitor and assess students to check for
understanding. Facilitate a class discussion about the activity.
Ask:
* How did you determine if regrouping was required in your addition
problem? (Answers may vary. I looked at both digits in the ones place, and if
the sum of the digits was more than 9, I knew that regrouping would be needed;
I looked at both digits in the tens place, and if the sum of the digits was more
than 9, I knew that regrouping would be needed; etc.)
* How was place value used in this activity? (Answers may vary. In order to
determine if regrouping was necessary, I had to add the digits in the ones place
to see if the sum was greater than 9, if the sum was greater than 9, I had to
regroup the 10; I added the digits in the tens place; etc.)
Explore/Explain
Activity 2:
1. Distribute handout: Story Problem Board and Recording Sheet to each student.
Instruct students not to write their name on the handout. Assign each student a
number and instruct them to record that number in the upper left hand corner of their
handout.
2. Instruct students to create and record a two digit addition story situation and
question related to the illustration on their handout: Story Problem Board and
14
Grade 02
Unit 06: Addition and Subtraction with Algorithms
Recording Sheet. Emphasize the importance of providing the necessary
information to be able to answer their question without giving the exact answer in the
story information. Remind students to use mathematical language in their problem
and question and that all numbers involved in the problem must be two-digit
numbers.
3. Allow time for students to complete the task. If more room is needed, students may
use the back of the handout. Monitor and assess students to check for
understanding.
4. Distribute a quarter-sheet of blank paper to each student. Instruct students to record
their assigned number in the upper left hand corner of the paper, a number sentence
that could be used to solve their problem from handout: Story Problem Board and
Recording Sheet, and the solution process to solve their problem. Explain to
students that this paper will serve as an answer key for their problem, so it is
important to be very neat, showing all work, as well as a number sentence. Allow
time for students to complete the task. Monitor and assess students to check for
understanding.
5. Collect handout: Story Problem Board and Recording Sheet and the answer key
from each student. Verify the solution process of each student’s key as these will be
used for future instruction.
What’s the teacher doing?
What are the students doing?
 Leading discussions
 Listening to class discussions
 Putting students in groups.
 Participating in class discussions
 Monitoring groups.
 Recording the algorithms and
pictorials
 Working cooperatively with their
partners
Phase: Explore and Explain


Materials:
Math Journal
Chart paper


Handouts:
Buying Trees(1 per student and
teacher)
Who Sold the Most Candy Bars? (1
per student)
Day 5
Adding 3 & 4 addends showing partial sums vertically and horizontally, and the
traditional algorithm.
Activity 1:
Explore and Explain
Display the chart: Buying trees.
Have the class read the scenario out loud, then read the names of the trees and how
much they cost.
Tell the students that we will be using the addition algorithm to add 3 or 4 numbers
vertically, making sure to line the digits in the ones place and the digits in the tens place
up.
15
Grade 02
Unit 06: Addition and Subtraction with Algorithms
Using chart paper, create a place value chart to record 4 numbers in. Have the
students use their Math Journals to create the same chart. They should record as you
move through the activity.
Have different students tell you trees that they think the family should buy and record
them in the place value chart.
Hundreds
Tens
Ones
2
1
2
3
4
+2
3
1
5
7
8
1
Maple
Red Oak
Cypress
Birch
21
Ask:
* What is our first step to solve this addition problem? (Add the digits in the
ones place together.)
* What addition strategies could we use to add the digits in the ones
place together? (Answers will vary, add the 7 and the 1 to make 8, then add
the doubles fact 8 plus 8 and get 16 then add 5 more)
Remind the students that when we add numbers together they can be added in any
order.
* What is the sum of the digits in the ones place? (21)
* Can we record 21 in the ones place? (no) Why? (The 2 stands for 2 tens and
needs to be regrouped to the tens place, and the 1 stays in the ones place
because it is a one)
Have a student record the 1 in the ones place and the 2 above the tens place digits on
the chart.
* What is our next step in solving this addition problem? (Add the digits in
the tens place together.)
* What addition strategies could we use to add the digits in the ones
place together? (Answers will vary, skip count the 2’s and get 6, then add 4 to
6 and make a 10, then add 3 and get 13 tens)
* What is the sum of the digits in the tens place? ( 13 tens)
* How do we record 13 tens on the chart? (The 3 stands for 3 tens and goes in
the tens place and the 1 has to be regrouped to the hundreds place.)
Have a student record the 3 in the tens place and the 1in the hundreds place.)
* Will Danica’s family buy these four trees? (no) Why? (The family budgeted
one hundred dollars for trees and the total of these trees is over one hundred
dollars.)
Have the students record the numbers horizontally in their Math Journal.
*This is to show the students order of operations, that addends can be
decomposed and grouped in any order to produce the same sum.
Demonstrate writing the numbers horizontally on the chart paper.
16
Grade 02
Unit 06: Addition and Subtraction with Algorithms
Model and explain expanding each number, add the tens together and then the ones
together. Lastly add the tens and ones together.
This is an example:
21 + 35 + 47 + 28 =
(20+1)+(30+5)+(40+7)+(20+8)
(20+30+40+20)+(1+5+7+8)
110+21=
131
Therefore, 21+35+47+28=131.
Continue the activity of choosing 3 or 4 trees to add together using the algorithm to find
the trees that Danica’s family can purchase.
Activity 2:
Partner Work: Distribute the handout: Who Sold the Most Candy Bars? Explain to
the students that they are going to work together to use the candy bar chart to record
the candy bars each student sold on the place value charts below. Then they are going
to justify, using words, how they know that that student sold the most.
Allow time for students to complete the activity. Check over the students work together.
What’s the teacher doing?
What are the students doing?
 Modeling for the students adding 3
 Listening and participating in
and 4 numbers.
discussions.
 Explaining the steps for adding the
 Recording addition problems neatly
numbers as they are modeled.
in their Math Journals.
 Leading discussions.
 Working cooperatively with
partners.
 Pairing students.
 Using addition strategies to add the
 Monitoring and assessing students
problems.
work.
Phase Engage & Explore/Explain

Materials:
Base ten blocks or place value
discs



Handouts:
Subtraction Poem (1 per student
and teacher
Withdrawing from the Family
Savings Account (1 per student and
teacher)
More Smith Family Emergencies (1
per student and teacher)
17
Grade 02
Unit 06: Addition and Subtraction with Algorithms
Day 6
Introduce subtraction of two-digit numbers using base tens or place value discs
and the traditional algorithm .
This website: http://nlvm.usu.edu/en/nav/grade_g_1.html has a great tool Base-Ten
Blocks Subtraction to project and use while practicing subtraction with regrouping
number problems. Just click and drag to enclose ten units or ones (or ten longs or tens)
and it regroups the base ten blocks. For subtracting, they move a 10-long or 100-flat
over and it breaks up before the eyes. Then, it shows each step with the traditional
algorithm too.
Engage
Activity 1:
Distribute the handout: Subtraction Poem
Read the poem together.
Show the students the youtube video: https://www.youtube.com/watch?v=wphuhM6bMg of the poem put to music.
Explore/Explain
Activity 2:
Distribute base ten blocks and the handout: Withdrawing from the Family Savings
Account to each student.
Display the scenario: Withdrawing from the Family Savings Account
Read and discuss the scenario to the students.
Tell the students that they are going to use their base ten blocks to subtract each
withdrawal the family makes from the account in the month of March and record the
numbers to subtract in the place value box, making sure to line up the numbers.
The teacher should project the beginning balance for the students to see.
Have the students read the beginning balance and then build it on their desks.
The teacher should also project the scenario: Withdrawing from the Family Savings
Account and show and work the algorithm for each withdrawal modeling for the
students.
l l l l l l l l
l l
. . . . .
. . . .
Read the first emergency.
Ask:* How will we show the withdrawal the family made? (by subtracting $25
from $98)
* Where do we start to subtract $25 from $98? (In the ones place.)
Have the students look at the Subtraction Poem and decide what to do.
* Are their more on the top or more on the floor? (the top)
* What is the rhyme for this problem? (More on the top, no need to stop)
Tell the students that this means we can remove 5 from 8.
18
Grade 02
Unit 06: Addition and Subtraction with Algorithms
* How many ones are we going to remove from the ones place? (5)
Model for the students how to count out 5 ones and move them off.
Then have the students remove 5 ones from their $98.
* What do we do next? (subtract 2 tens from the tens place)
Model for the students removing two tens then have the students do it on their desks.
* Are we finished? (yes) How do you know? (We are subtracting $25 which is 2 tens
and 5 ones and we have done that.)
* What is the Smith’s saving account balance down to now? ($73)
Read the second emergency.
Ask:
* How much money do they have to withdraw from their savings account to
pay for the water heater part? ($16)
* Where do we start to subtract $16 from $73? (in the ones place)
Tell the students to look at the Subtraction Poem and see which rhyme tells them what
to do.
* Are their more on the top or more on the floor? (the floor)
* What’s the rhyme? (More on the floor go next door and get 10 more.)
Model how to borrow a ten, count out ten ones, and make an even trade.
Have the students borrow a ten, count out ten ones and make an even trade on their
desk.
* How many ones are in the ones place now? (13)
* Do we have enough ones in our ones place to remove 6 ones now? (yes)
Model removing 6 ones.
Have the students remove 6 ones.
* How many ones are left in the ones place? (7)
. . .
l l l l l l
l
. . . .
. . . . . .
* What is our next step? (subtracting a ten from the tens place)
* Are their enough tens to subtract 1 ten from the tens place? (yes)
Model removing a ten from the tens place.
Have the students remove a ten from their tens place.
* How many tens are left in the tens place? (5)
* What is the Smith’s saving account balance down to now? ($57)
Read the third emergency.
Ask:
* How much money do they have to withdraw from their savings account to
pay the repairman to fix the oven? ($38)
* Where do we start to subtract $38 from $57? (in the ones place)
19
Grade 02
Unit 06: Addition and Subtraction with Algorithms
Tell the students to look at the Subtraction Poem and see which rhyme tells them what
to do.
* Are their more on the top or more on the floor? (the floor)
* What’s the rhyme? (More on the floor go next door and get 10 more.)
Model how to borrow a ten, count out ten ones, and make an even trade.
Have the students borrow a ten, count out ten ones and make an even trade on their
desk.
* How many ones are in the ones place now? (17)
* Do we have enough ones in our ones place to remove 8 ones now? (yes)
Model removing 8 ones.
Have the students remove 8 ones.
* How many ones are left in the ones place? (9)
* What is our next step? (subtracting a ten from the tens place)
* Are their enough tens to subtract 3 ten from the tens place? (yes)
Model removing 3 tens from the tens place.
Have the students remove 3 tens from their tens place.
* How many tens are left in the tens place? (1)
* What is the Smith’s saving account balance down to now? ($19)
Turn and Talk to your neighbor about what the Smiths can do to increase the balance
in their saving account. Ask different groups to share what they discussed.
Activity 3:
Partner Work: Place the students in pairs. Distribute the handout: More Smith Family
Emergencies. Instruct the students to work with their partner to determine what the
Smith’s Savings Account balance after each emergency in the month of June and
September. Allow students time to complete the activity.
Have a class discussion and check over the handout together.
What’s the teacher doing?
 Modeling subtraction with the base
ten blocks and the algorithm.
 Explaining the steps for regrouping
subtraction problems.
 Leading class discussions.
 Pairing students.
 Monitoring and assessing students
work.
What are the students doing?
 Listening and participating in class
discussions.
 Building, regrouping and removing
numbers with the base ten blocks.
 Recording the subtraction
algorithm on the handouts.
 Working cooperatively with their
partner.
Phase Four Elaborate

Materials:
Pencils and erasers

Handouts:
Target and Walmart Circulars (1
per teacher)
20
Grade 02
Unit 06: Addition and Subtraction with Algorithms




Target and Walmart Circulars (1
per 2 students)
Comparison Items (1 per student)
Comparison Items (1 per teacher)
Comparison Items Key (1 per
teacher)
Day 7 Activity:
Students demonstrate two-digit subtraction number sentences, generate a story from a
given number sentence and checking account with new balance after withdrawing an
amount of money.
Instructional Procedures:
1. Display teacher resource: Target and Walmart Circulars. Explain to students that
they will be looking at items in both circulars and will be using subtraction methods to
compare prices. Allow time for students to review the circulars and share their thoughts.
2. Place students in pairs. Distribute handout: Target and Walmart Circulars to each
pair and handout: Comparison Items to each student. Display teacher resource:
Comparison Items.
3. Refer to the displayed teacher resource: Comparison Items to facilitate a class
discussion on how to complete each section of the handout. Instruct students to work
independently to solve the number sentence on handout: Comparison Items. Then
have students work in pairs to create a story problem from the given number sentence
using handout: Target and Walmart Circulars as a guide.
4. Allow time for students to work the first problem and generate a story from the given
number sentence. Monitor and assess students to check for understanding.
5. Facilitate a class discussion to review the first problem with the class.
Ask:
 What items cost $89 and $75? (A tablet from Target and a tablet from Walmart)
 How could you solve this problem? (Answers may vary. Open number line,
traditional algorithm, hundreds chart, etc.)
 What answer did you get? ($9)
 How could you write a word problem to match the number sentence?
(Answers may vary. Example: Peter wants to purchase a tablet for his brother for
his birthday. He looked at the circular for Walmart and Target. The tablet at
Walmart costs $75 and the tablet at Target costs $89. How much money will he
be saving if he purchased the tablet from Walmart than from Target?)
Facilitate a discussion inviting multiple students to share their strategy and word
problem. Allow students to display their recording sheet and explain their work.
Instruct the class to evaluate the student’s displayed recording sheet to ensure that
the strategy has been explained thoroughly. Allow time for students to self-correct, if
necessary.
21
Grade 02
Unit 06: Addition and Subtraction with Algorithms
6. Instruct students to continue working independently to complete the remaining
problems.
7. Monitor and assess students to check for understanding.
What’s the teacher doing?
 Discussing vocabulary words such
as savings, withdraw, difference,
number sentence, subtraction, etc.
 Explain and model activity
expectations.
 Monitor and assess students to
check for understanding.
What are the students doing?

Participating in class discussions.
 Working on activity independently
and in pairs.
Phase Four Elaborate

Materials:
Pencils, erasers




Handouts:
Restaurant Menu (1 per teacher)
Restaurant Menu (1 per student
pair)
Restaurant Menu Recording Sheet
(1 per teacher)
Restaurant Menu Recording Sheet
(1 per student)
Day 8 Activity:
Students will review two-digit subtraction with multi-step addition and subtraction with
one and two digits and generate a story problem from a given number sentence.
Instructional Procedures:
1. Display teacher resource: Restaurant Menu. Allow time for students to review the
menu items and prices.
2. Place students in pairs. Distribute handout: Restaurant Menu to each pair and
handout: Restaurant Menu Recording Sheet to each student. Display teacher
resource: Restaurant Menu Recording Sheet.
3. Instruct students to work independently to generate story problems from the given
number sentence on handout: Restaurant Menu Recording Sheet, using handout:
Restaurant Menu to determine the cost of each food item. Refer to the displayed
teacher resource: Restaurant Menu Recording Sheet to facilitate a class discussion
on how to complete each section of the handout.
4. Allow time for students to work the first problems independently. Monitor and assess
students to check for understanding.
22
Grade 02
Unit 06: Addition and Subtraction with Algorithms
5. Facilitate a class discussion to review the first problem with the class.
Ask:
 Which food item costs $15 and $3? (Turkey Sandwich and Fries)
 What story problem could be represented by the number sentence?
(Answers may vary. Example: Betsy bought a turkey sandwich for $15 and fries
for $3. How much did her lunch cost?)
 Explain how the number sentence represents the problem situation.
(Answers may vary. According to the Restaurant Menu given, the cost of the
turkey sandwich costs $15 and fries costs $3. I created a story problem that
represented the number line given).
Facilitate a discussion inviting multiple students to share their story problem. Allow
students to display their recording sheet and explain how the number sentence
represents the problem situation. Instruct the class to evaluate the student’s displayed
recording sheet to ensure that the explanation has been explained thoroughly. Allow
time for students to self-correct, if necessary.
6. Instruct students to continue working independently to complete the remaining
problems.
7. Monitor and assess students to check for understanding.
What’s the teacher doing?
 Discussing vocabulary words such
as savings, withdraw, difference,
number sentence, subtraction, etc.
 Explain and model activity
expectations.
 Monitor and assess students to
check for understanding.
What are the students doing?

Participating in class discussions.
 Working on activity independently
and in pairs.
Phase Two Explore/Explain

Materials:
Pencils, erasers



Handouts:
Three-Digit Addition Recording
Sheet 1 (1 per teacher)
Three-Digit Addition Recording
Sheet 1 (1 per student)
Three-Digit Addition Recording
Sheet 1 KEY (1 per teacher)
23
Grade 02
Unit 06: Addition and Subtraction with Algorithms
Day 9 Activity:
Students demonstrate three-digit addition algorithm modeling with an open number line
and then generating a story problem based on the given number sentence.
Instructional Procedures:
1. Facilitate a class discussion to demonstrate the process of solving and recording
addition problems using a number line model, and then generate a story problem to
represent the number sentence.
2. Display teacher resource: Three-Digit Addition Recording Sheet 1 for students to
see. Refer to the displayed addition problem: 350 + 287 = ?
3. Invite several students to share strategies that could be used to solve the problem.
Facilitate a discussion to compare the strategies shared and to reinforce the
understanding that there are multiple flexible methods that could be used to solve threedigit addition problems.
4. Explain to students that while there are many correct strategies that have been
shared, for demonstration purposes, the class will all record the same strategy in the
top portion of the handout: Three-Digit Addition Recording Sheet 1.
5. Demonstrate solving the problem on the number line by beginning with 350, adding
two groups of hundreds from the addend 287, and then adding eight groups of ten from
addend 287, and finally adding seven from addend 287. Instruct students to replicate
the number line model on their handout: Three-Digit Addition Recording Sheet 1.
6. Demonstrate recording the strategy number sentence: 350 + 200 + 80 + 7 = 637.
Refer to the number line model as you record each addend of the strategy number
sentence.
7. Facilitate a discussion to explain to students how to write a numerical explanation of
the strategy using words to justify the solution.
Ask:
 According to the number line model, what starting number was used? (350)
 What was the next step in the strategy modeled on the number line? (Add
the 200 from the addend 287.)
 What was the next step in the strategy modeled on the number line? (Add
80 from the addend 287.)
 What was the last step in the strategy modeled on the number line? (Add 7
from the addend 287.)
 According to the number line, what is the sum of 350 + 287? (637)
 Does this number match the total determined using one of your strategies?
(Answers may vary.)
Instruct students to record the answer in the “Answer” section of the recording
sheet.
24
Grade 02
Unit 06: Addition and Subtraction with Algorithms
8. Refer students to the bottom portion of the handout: Three-Digit Addition
Recording Sheet 1. Place students in pairs. Explain to students that they will work with
a partner to create a story problem from the given number sentence. Then instruct
students to complete the rest of the recording sheet individually. Remind students of
earlier discussion where multiple strategies were shared. Explain to students that they
will record a different number line model, strategy answer sentence, generate a story
problem and numerical explanation for the same problem: 350 + 287 = ?
9. Monitor and assess students to check for understanding. Facilitate individual
discussions to guide students’ wording of their numerical explanation as necessary.
Allow time for students to complete all sections of the recording sheet.
10. Facilitate a class discussion to review flexible methods and story problems that may
be used to solve addition problems and the connection to the base-ten number system.
Encourage students to discuss the similarities and differences in each strategy,
highlighting efficient strategies and encouraging students to understand their peers’
thinking.
Ask:
 Of the strategies shared, which strategy or strategies could be considered
efficient? Answers may vary.
 What makes the strategy efficient? Answers may vary. The strategy included
jumping by larger numbers; the strategy did not take many steps to complete; the
strategy involved friendly numbers so the sum could be found mentally; etc.
What’s the teacher doing?
 Explain and model activity
expectations.
 Monitor and assess students to
check for understanding.
 Ask higher order thinking questions.
What are the students doing?

Participate in class discussions.
 Work independently and in pairs.
Phase Two Explore/Explain

Materials:
https://www.youtube.com/watch?v=B
kzoUfyAXDU (Three-digit
subtraction with regrouping)


Handouts:
Three-Digit Subtraction Recording
Sheet 1 (1 per teacher)
Three-Digit Subtraction Recording
Sheet (1 per student)
Day 10 Activity:
Students will demonstrate three-digit subtraction algorithm and then generate a story
problem based on the given number sentence.
Instructional Procedures:
1. Facilitate a class discussion to demonstrate the process of solving and recording
subtraction problems using the base-ten chart and then generate a story problem to
25
Grade 02
Unit 06: Addition and Subtraction with Algorithms
represent the number sentence.
2. Display teacher resource: Three-Digit Subtraction Recording Sheet 1 for students
to see. Refer to the displayed subtraction number sentence on the board: 343 – 178.
3. Demonstrate how to find the difference by using the base-ten chart.
Also found on https://www.youtube.com/watch?v=BkzoUfyAXDU
H
2 13 13
343
-178
?
=
1
T
O
||||
. . .
||||| . . . . .
||||| . . . . .
6
5
4. Invite several students to share a story problem using the given number sentence.
5. After a few students have shared, allow students time to write and complete their
story problem on the bottom portion of the handout: Three-Digit Subtraction
Recording Sheet 1.
6. Instruct students to complete the rest of the recording sheet individually. Remind
students to use the base-ten chart to help them find the difference.
7. Monitor and assess students to check for understanding. Facilitate individual
discussions to guide students’ wording of their story problem as necessary. Allow time
for students to complete all sections of the recording sheet.
8. Facilitate a class discussion to review three-digit subtraction using the base-ten chart.
Ask:
 Who can explain how they used the base-ten number system to solve the
three-digit subtraction number sentence? Answers may vary. I started in the
ones place and decided if I needed to regroup.
What’s the teacher doing?
 Explain and model activity
expectations.
 Monitor and assess students to
check for understanding.
What are the students doing?
 Participate in class discussions.
 Work independently and in pairs.
Phase Two and Three Explore/Explain


Materials:
Pencils, erasers
Math journals or notebook paper
Handouts:
26
Grade 02
Unit 06: Addition and Subtraction with Algorithms
Day 11 Activity:
Students will demonstrate three-digit subtraction across zeros with base tens using
Take a Penny strategy. (*Optional: Continue solving three-digit subtraction across zeros
using base-ten models).
Prior to instruction:
1. Distribute math journals or notebook paper for students to take notes.
Instructional Procedures:
1. Review with student’s ways of solving three-digit subtraction problems.
Ask:
 What are some ways to solve two- and three-digit subtraction problems?
(Answers may vary. Traditional algorithm, drawing using a hundreds chart, etc.)
2. Explain to students that today, they will be learning another strategy called, Take a
Penny.
Say: We use Take a Penny when subtracting across zeros. Take a Penny means
to take 1. Taking a Penny will take your number back one.
3. Demonstrate by writing examples on the board.
Say: In order to Take a Penny, first think of money.
Ask:
 If you take a penny from $1.00, how much do you have now? ($0.99)
 If you take a penny from $2.00, how much do you have now? ($1.99)
 If you take a penny from $5.00, how much do you have now? ($4.99)
 If you take a penny from $10.00, how much do you have now? ($9.99)
Say: Now think of whole numbers:
Ask:
 If you take a penny from 10, what do you have now? (9)
 If you take a penny from 20, what do you have now? (19)
 If you take a penny from 50, what do you have now? (49)
 If you take a penny from 100, what do you have now? (99)
 If you take a penny from 800, what do you have now? (799)
4. Display a subtraction number sentence on the board: 300 – 245 = ?
Say: In the “Old School” (traditional algorithm) way, we would stack these numbers
and borrow across zeros.
5. Model the traditional subtraction algorithm to students:
 Circle the largest number in each place.
 Refer to subtraction anchor chart, Big on Top?
No Need to Stop!
Big on the Floor?
Go Next Door!
 Can you take one ten? Then go to the hundreds place.
27
Grade 02
Unit 06: Addition and Subtraction with Algorithms


Take one hundred. That’s ten tens more.
Now you can finally subtract.
9
2 10 10
300
-2 4 5
55

Finally, check with addition:
1 1
245
+55
300
6. Next, model the Take a Penny strategy.
Say: We are going to try, “Take a Penny” strategy. Just like the “Old School” way,
we are going to stack these numbers. Make sure the numbers are lined up in the
correct places.
3 0 0 -1 = 2 9 9
- 2 4 5 -1 = -2 4 4
55



Circle the largest number in each place.
Take a penny from 300. Say: You must be fair and do the same on the
bottom as you would the top, so take a penny from 245.
Finally, subtract without regrouping.
7. Display another three-digit subtraction across zeros number sentence: 400 – 178 = ?
Say: Let’s try “Take a Penny” with this number sentence. First, stack it up. Make
sure the numbers are in the correct place.
400
-1 7 8
Say: Next, circle the largest number in each place.
400
-1 7 8
Say: Now take a penny from 400. Remember you must be fair. What you do on the
top, you must do on the bottom.
4 0 0 -1
-1 7 8 -1
399
-1 7 7
222
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Grade 02
Unit 06: Addition and Subtraction with Algorithms
Say: Finally, you subtract without regrouping.
8. Display another three-digit subtraction across zeros on the board for students to
complete individually: 700-376 = ?
9. Allow time for students to complete the problem.
10. Monitor and assess students to check for understanding. Facilitate individual
discussions to guide students’ through each step as necessary.
11. Facilitate a class discussion to review three-digit subtraction across zero problem.
Ask:
 What is the first step in solving this problem using the “Take a Penny”
strategy? (Stack it up and make sure the numbers are in the correct places.)
 What is the second step in solving this problem? (Circle the largest number
in each place.)
 Who remembers the next step? (Take a penny from 700. To be fair, you must
also take a penny from 376.)
 Finally, what happens last? (We subtract the 375 from 699 without regrouping.)
 How do we know if we have the right answer? (Use addition to see if you
have the same numbers.)
 What is the answer to 700-376? (324)
12. Display a few three-digit subtraction across zeros on the board for students to
complete individually or with a partner.
 1,000-867 = ?
 900-452 = ?
 500-198 = ?
 600-355 = ?
13. Monitor and assess students to check for understanding. Allow students time to
complete the problems. When students are complete, go over each problem with the
students.
What’s the teacher doing?
What are the students doing?
 Explain and model activity

Participate in class discussions.
expectations.
 Work independently and in pairs.
 Monitor and assess students to
 Take notes.
check for understanding through
discussions and questions.
Phase Four Elaborate



Materials:
White construction paper cut in half
(about 12)
Pencils, erasers
Clipboards


Handouts:
Addition and Subtraction Number
Sentence Sheet (1 per student
pair)
Addition and Subtraction Word
Problem Practice Scoot (1 per
29
Grade 02
Unit 06: Addition and Subtraction with Algorithms


teacher)
Addition and Subtraction Word
Problem Practice Scoot KEY (1 per
teacher)
Addition and Subtraction Word
Problem Practice Scoot Recording
Sheet (1 per student)
Day 12 Activity:
Students will demonstrate mixed addition/subtraction multi-step problems with
subtraction across zeros and generate story problems together.
Prior to instruction:
1. Cut the Addition and Subtraction Number Sentence Sheet along the dotted lines
and cut at least 12 sheets of white construction paper in half.
Instructional Procedures:
1. Place students in pairs. Distribute one Addition and Subtraction Number
Sentence Sheet to each pair. Explain that each student pair will be given either a threedigit addition or subtraction number sentence. Next, distribute a sheet of white
construction paper to each pair. Each pair of students is responsible for generating a
story problem that matches the number sentence given. They are to write the story
problem on the white sheet of construction paper. The students must then work
together to solve their problem. They must show work using a strategy such as drawing
a base-ten chart, using the traditional algorithm, or take a penny, etc.
2. When students are finished solving their problem, invite students to share their story
problem and their problem solving strategy. Tell students to read their story problem to
the class without showing them the given number sentence.
Ask:
 What information do we know about the problem? (Answers may vary)
 What operation do we need to do in order to solve the problem? (Answers
may vary)
 What strategy did you use to help you solve your problem? (Answers may
vary)
 Is there another way to solve this problem? (Answers may vary)
After students explain the steps they took to solve their story problem, have them reveal
their number sentence.
3. Once several students have shared, explain to them that there are multiple ways to
solve story problems and the importance of showing work.
4. Explain to students that the next activity is called Addition and Subtraction Word
Problem Practice Scoot.
5. Place the Addition and Subtraction Word Problem Practice Scoot on every other
30
Grade 02
Unit 06: Addition and Subtraction with Algorithms
desk. Have students start at their own desk, recording and solving the problem using
the Addition and Subtraction Word Problem Practice Scoot Recording Sheet at
their desk in the box with the matching letter on the recording sheet. Students will move
to a new desk when the teacher says, “Scoot!” When everyone has rotated through all
of the problems, go over the answers as a class.
What’s the teacher doing?
 Explain and model activity
expectations.
 Monitor and assess students to
check for understanding through
discussions and questions.
Phase Five: Evaluate
What are the students doing?

Participate in class discussions.
 Work independently and in pairs.
 Explore multiple ways of solving
word problems.
Materials:
 Pencils
 Erasers
Day 13 Activity:

Handouts:
Performance Assessment #2
Students will be completing the Performance Assessment #2.
What’s the teacher doing?



Setting clear expectations for testing
environment
Walking around and monitoring to
check for understanding
Answering any questions students
may have
What are the students doing?


Completing Performance
Assessment #2
Working quietly and independently
Phase Two Explore/Explain
Materials:
 Bunny Money by Rosemary Wells
https://www.youtube.com/watch?v=b
cVaypXBEqg
 The Berenstain Bears-Trouble With
Money by Stand and Jan Berenstain
https://www.youtube.com/watch?v=OvF
7E87Ig3I
 Alexander, Who Used be Be Rich
Last Sunday by Judith Viorst
https://www.youtube.com/watch?v=4ep
ex3iMeDM



Handouts:
Problem Solving Sheet 1 (1 per
teacher)
Problem Solving Sheet 1 (1 per
student)
Problem Solving Sheet 1 KEY (1
per teacher)
31
Grade 02
Unit 06: Addition and Subtraction with Algorithms
Day 14 Activity:
Students will be working on word problems with concepts in finance such as savings
accounts, checking accounts, withdrawals, deposits, earnings and balance.
Instructional Procedures:
1. Introduce the concept of finance with one of these children’s book: Bunny Money by
Rosemary Wells, The Berenstain Bears’ Trouble with Money by Stan and Jan
Berenstain, or Alexander Who Used to Be Rich Last Sunday by Judith Viorst.
2. As you’re reading or showing the story on youtube, stop and discuss some of
vocabulary words such as saving, spending, deposit, withdraw and earnings with the
students.
 Saving- an amount of something that is not spent or used.
 Spending- to use money to pay for something.
 Deposit- to put money in a bank account.
 Withdraw- to remove money from a bank account.
 Earnings- money received as wages or gained as profit.
3. Explain to students that today, they will be working on story problems with financial
vocabulary.
4. Distribute Problem Solving Sheet 1 to each student. Display Problem Solving
Sheet 1 and go through the first two problems together as a whole group.
Jack saves $10 a month for a new video game. How much will he save in 7 months?
Ask:
 What information is given? (Jack saves $10/month).
 What do we need to find out? (We need to know how much he will save in 7
months).
 If Jack is “saving,” what does that mean to his total every month? (It gets
bigger).
 What operation do we use in this problem, and how do you know? (Addition
because Jack is saving money every month. The total will get bigger, so we have
to add).
 What numbers do we need to add in order to solve this problem? (We need
to add $10 seven times. $10+$10+$10+$10+$10+$10+$10 = $70
 How much will Jack save in 7 months? ($70)
Collin has $789 in his savings account. Christine has $132 more than Collin in her
savings account. Jenny has $256 less than Christine in her savings account. How much
money does Jenny have in her savings account?
Ask:
 What information is given? (Collin has $789 in his savings account)
 What do we need to find out? (We need to know how much Jenny has in her
savings account)
 What information do we need to find out first? (We need to find out how
much money Christine has in her savings account.)
 How do we find this out? (Since Christine has $132 more than Collin and we
32
Grade 02
Unit 06: Addition and Subtraction with Algorithms



already know how much Collin has, we need to add $132 + $789 = $921)
How much does Christine have in her savings account? ($921)
How do we find out how much money Jenny has in her savings account?
(Since Jenny has $256 less than Christine, then we need to subtract $256 from
$921. $921-$256 = $665)
How much does Jenny have in her savings account? Do you agree and
why? ($665) Yes, because we ended with less than we started with.
5. Explain to students that they will be working with a partner to solve the rest of the
story problems. They must show their work.
6. Monitor and assess students to check for understanding. Allow students time to
complete the problems. When students are complete, go over the problems with the
students.
What’s the teacher doing?
 Explain and model activity
expectations.
 Monitor and assess students to
check for understanding through
discussions and questions.
What are the students doing?
 Participate in class discussions.
 Work in whole group and
independently.
 Explore multiple ways of solving
word problems.
Phase Five: Evaluation

Materials:
Pencils, erasers

Handouts:
Performance Assessment #1
Day 15 Activity:
Students will be completing the Performance Assessment #1.
What’s the teacher doing?
 Setting clear expectations for testing
environment
 Walking around and monitoring to
check for understanding
 Answering any questions students
may have
What are the students doing?
 Completing Performance
Assessment #1
 Working quietly and independently
33