SECOND GRADE > 2.NBT.5 > TEACHER GUIDE
TEACHER GUIDE TO CLARIFICATION
2.NBT.5
Use place value understanding and properties of operations to add and subtract.
2.NBT.5 Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction.
Defining Place Value Strategies
There are multiple ways students can use and apply their knowledge of Place Value. This
standard calls for students to use strategies. Students can use strategies, manipulatives
and pictorial representations. (Below are 4 strategies named in standard 1.OA.6)
Example 28 + 67
Student 1
Decomposing Adding tens and ones
20 + 60 = 80
8 + 7 = 15
80 + 15 = 95
Student 3
Making 10
28 + 67
28 + 2 + 65
28 + 2=30
30 + 65 = 95
Decompose the 67
into 2 and 65 so I
can have 2 ones to
make 28 a 30.
Student 2
Counting on by 10
28 + 10 + 10 + 10 + 10 + 10 + 10
88 + 7 = 95
Student 4
Create easier or known sums
In grade two the use of a visual like baseten blocks would be beneficial to show how you can move the ones around
30 + 60 = 90
plus 5 more ones = 95
28 + 67
Move 2
When teaching these Place Value strategies the approach the teacher takes is just as important. A recommendation is to let students solve the problem in any way that works for them, then elaborate on how they solved the problem. Given the problem 32 + 25 students can solve the problem a few different ways. It is up to the teacher to recognize how they solved it and then identify that strategy to the other students. This promotes student  discovery learning. The teacher then truly becomes a facilitator of learning.
In this grade level, the conceptual understanding is being developed. In grade 4, students will learn the
standard algorithm with regrouping
Addition based on Place Value 32 + 25
Decomposing Adding tens and ones
Place Value I can break the numbers into tens and ones.
I can breaks the numbers into tens 30 + 20 which = 50
I can break the numbers into ones 2 + 5 which = 7
My answer is 57
Count on
Place Value I can count on
I will start with 32 and count on the tens
32 + 20 = 52
Then count on the ones
52 + 5 = 57
Making Ten
Place Value I can make a ten
I will start with 32 and add the 5 ones which leaves me with 20. Now I have 37 and I still need 3 to get to the next ten 40, so I borrowed 3 from 20 and I am left with 17. 40 + 17 = 57
Subtraction Based on Place Value 61 – 27
Open Number Line
Place Value with an open number line (this is interesting to see how the students “hop” up
the number line) This will build number sense and eventually, students will not need the
number line visually and they can solve this subtraction problem mentally.
Start with 27
Start with 27 and count up to
the target number 61
Add up by tens and ones (mental version of open number line)
Place Value
27 + 30 = 57
57 + 4 = 61
Add 30 + 4 = 34 is the answer
Subtract by tens and ones (mental version of open number line)
Place Value
61  27
61 – 10 = 51, 51 – 10 = 41, 41 – 7 = 34
Coherence and Connections: Need to Know
Grade Below
3.NBT.2
1.NBT.4
1.NBT.5
1.NBT.6
Grade Level
2.NBT.5
2.OA.1
2.OA.
Grade Above
This is fluency Standard
Fluency Expectations or Examples of Culminating Standards
2.NBT.B.5 Fluently add and subtract within 100 using strategies based on place
value, properties of operations, and/or the relationship between addition and
subtraction.
Students can also show their fluency using an efficient, general algorithm.18
18 For the difference between a computation strategy and a computation algorithm, see the glossary of
the standards (page 85, under the letter “c” for “computation”).
PARCC Draft Model Content Frameworks: Mathematics Grades K2
So, let’s go to the Standards Document glossary pg. 85
Computation algorithm. A set of predefined steps applicable to a class of problems that gives the correct result in every case when the steps are carried out correctly. See also: computation strategy.
Computation strategy. Purposeful manipulations that may be chosen for specific problems, may not have a fixed order, and may be aimed at converting one problem into another. See also: computation algorithm.
Examples of Major WithinGrade Dependencies
Understanding place value (cluster 2.NBT.A) is the foundation for using place value
understanding and the properties of operations to add and subtract (cluster 2.NBT.B).
(Mastery of the two clusters can grow over time in tandem with one
another.) Adding and subtracting within 1,000 (2.NBT.B.7) involves adding or subtracting hundreds with hundreds, tens with tens and ones with ones, sometimes composing or decomposing tens or hundreds. These ideas and methods rest on an understanding of the place value units (2.NBT.A.1, building on 1.NBT.A.2).
PARCC Draft Model Content Frameworks: Mathematics Grades K2
Use place value understanding and properties of operations to add and subtract
Students become fluent in twodigit addition and subtraction.2.NBT.5, 2.NBT.6.
Representations such as manipulative materials and drawings may be used to support reasoning and explanations about addition and subtraction with threedigit numbers. 2.NBT.7
When students add ones to ones, tens to tens, and hundreds to hundreds they are
implicitly using a general method based on place value and the associative and
commutative properties of addition.
Common Core Standards Writing Team. (2013, September 19).
Progressions for the Common Core State Standards in Mathematics(draft). K5 Number and Operations in Base 10. Tucson, AZ: Institute for Mathematics and Educations, University of Arizona.
For this standard students are only required to add and subtract within 100.
Also check out Student Achievement Partners Coherence Map.
FYI:
2.NBT.5 is from
the 2.NBT.B
cluster
HOT Questions

How many tens are in the sum of the addition problem 16 + 39

How many ones are in the difference of the subtraction problem 23 – 18

Solve the addition problem two different ways 67 + 24

Why would I split up the numbers this way in order to add?
27 + 14
20 + 7 + 10 + 3 + 1 =
5. Explain how you can move the baseten blocks in order to solve the addition problem
Additional Resources
Illustrative Mathematics
http://tasks.illustrativemathematics.org/contentstandards/2/NBT/B/5/tasks/1071
http://tasks.illustrativemathematics.org/contentstandards/2/NBT/B/5/tasks/1292
http://tasks.illustrativemathematics.org/contentstandards/2/NBT/B/5/tasks/1309
http://tasks.illustrativemathematics.org/contentstandards/2/NBT/B/5/tasks/2068
Inside Mathematics
https://www.insidemathematics.org/commoncoreresources/2ndgrade
Achieve the Core
https://achievethecore.org/page/907/curioussubtractiontask
Hawaii
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http://standardstoolkit.k12.hi.us/classproblem2nbt52nbt9/
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