Students develop strategies based on place value, properties of operations, and the operational relationship between addition and subtraction to add and subtract within 100 fluently. Students will use these strategies to add up to four twodigit numbers and explain why these strategies work. Students also explore categorical data.
Math
Unit 2
2nd Grade
In Unit 2, 2nd grade students build on their addition and subtraction work to develop and use strategies to add and subtract within 100 fluently. By the end of 2nd grade students are expected to fluently add and subtract within 100 using strategies based on place value, properties or operations, and the relationship between addition and subtraction (2.NBT.B.5). By extending their fluency work within 20 from Unit 1, students will use some of the strategies and understandings from their work within 100.
In Topic A, students begin the unit by adding and subtracting with multiples of ten. This serves as a bridge from students Grade 1 work where they used place value understandings and properties of operations to add and subtract. They also build off their Unit 1 work and apply make a ten strategies to adding twodigit numbers within 50.
In Topic B, the focus is on strategies for adding within 100. In this topic students will use concrete manipulatives to represent their addition work and translate that to pictorial representations and then to more abstract representations. They will use their knowledge of tens and ones as they add as well. Students will also be introduced to the standard algorithm as a strategy but they are not expected to fluently use the standard algorithm in their Grade 2 math development.
In Topic C, students will focus on subtraction and similarly move through concrete representations to pictorial, using place value drawings, and later more abstract representations. Students will use their place value knowledge to subtract with up to one decomposition of a ten into 10 ones in order to subtract in situations where there are not enough ones. Students also explore how they can relate subtraction to addition in order to subtract.
Finally, in Topic C students build on the work with word problems by exploring compare problems within 100. They will build on their Unit 1 word problem work by continuing to use tape diagrams to represent the problem and using symbols to represent the unknown in their equations. In this topic students will culminate their work with exploring addition and subtraction within 100 by adding up to four twodigit numbers (2.NBT.B.6) and explain the strategies they used to solve addition and subtraction problems (2.NBT.B.9). Students also end the unit by exploring categorical data with picture graphs and bar graphs. Students learn about the structure of both graph types and learn to interpret and create them to answer and ask questions based on the given data (2.MD.D.10).
The work students explore in this unit provides students with a foundation for their work in future units in 2nd grade, most notably Unit 5 where they will extend their addition and subtraction strategies within 1,000. Students will continue to practice their fluency with 100 throughout their 2nd grade work as they solve word problems within 100, engage in work with measurement in Unit 3, and as they extend their place value understandings in Unit 4.
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The following assessments accompany Unit 2.
Have students complete the MidUnit Assessment .
Use the resources below to assess student understanding of the unit content and action plan for future units.
number bonds 

base ten blocks 
34 shown in base ten blocks

place value chart 

vertical way 

bar graph 

picture graph 

tape diagram 
Example: Armando buys 16 peppers for a barbecue. 7 of the peppers are red and the rest of the peppers are orange. How many orange peppers did Armando buy?

bar graph
categorical data
data
decompose
key
picture graph
To see all the vocabulary for Unit 2 , view our 2nd Grade Vocabulary Glossary.
Topic A: Adding & Subtracting with Multiples of Ten
Topic B: Strategies for Adding within 100
Topic C: Strategies for Subtracting within 100
Topic D: Working within 100 and Categorical Data
Key
Major Cluster
Supporting Cluster
Additional Cluster
CCSS.MATH.PRACTICE.MP1 — Make sense of problems and persevere in solving them.
CCSS.MATH.PRACTICE.MP2 — Reason abstractly and quantitatively.
CCSS.MATH.PRACTICE.MP3 — Construct viable arguments and critique the reasoning of others.
CCSS.MATH.PRACTICE.MP4 — Model with mathematics.
CCSS.MATH.PRACTICE.MP5 — Use appropriate tools strategically.
CCSS.MATH.PRACTICE.MP6 — Attend to precision.
CCSS.MATH.PRACTICE.MP7 — Look for and make use of structure.
CCSS.MATH.PRACTICE.MP8 — Look for and express regularity in repeated reasoning.
Unit 1
Adding and Subtracting Within 20
Unit 3
Measurement
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