2.NBT.B.9

Explain why addition and subtraction strategies work, using place value and the properties of operations. (Explanations may be supported by drawings or objects.)

 
45 Lesson(s)
   

Domino Addition: Understanding the Part/Part/Whole Relationship

2nd Grade Math » Unit: Addition and Subtraction Basic Training
2nd Grade Math » Unit: Addition and Subtraction Basic Training
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

The big idea of this lesson is the understanding that addition can be represented as parts of a whole and that we can use addition sentences to represent those parts.

 
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Reflections (1)
part part whole
   

The Neighbors of Doubles

2nd Grade Math » Unit: The Mission of Addition
2nd Grade Math » Unit: The Mission of Addition
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

The big idea of this lesson is that students can solve for near doubles by thinking of the related doubles fact.

 
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Resources (14)
 
Reflections (1)
neighbors of
   

Making a Ten

2nd Grade Math » Unit: The Mission of Addition
2nd Grade Math » Unit: The Mission of Addition
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

Making ten is one of the foundational strategies for developing flexible numerical thinking, accuracy, and efficiency.

 
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Resources (15)
 
Reflections (1)
screen shot 2013 12 19 at 9 58 29 am
   

Thinking Addition Facts to 18 to Subtract

2nd Grade Math » Unit: The Action of Subtraction
2nd Grade Math » Unit: The Action of Subtraction
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

Students apply their understanding of addition to solve related subtraction problems.

 
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Resources (13)
 
Reflections (1)
screen shot 2013 12 19 at 3 31 43 pm
   

Think About Subtracting Nothing

2nd Grade Math » Unit: The Action of Subtraction
2nd Grade Math » Unit: The Action of Subtraction
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

The big idea of this lesson is thinking about subtraction facts with 0, 1, and 2 as amounts less than a number.

 
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Resources (11)
 
Reflections (1)
screen shot 2013 12 19 at 12 47 01 pm
   

Double Trouble

2nd Grade Math » Unit: The Mission of Addition
2nd Grade Math » Unit: The Mission of Addition
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

The big idea of this lesson is that students can think about doubles facts as world situations to help commit them to memory.

 
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Reflections (1)
bugre americanu
   

Subtracting Doubles

2nd Grade Math » Unit: The Action of Subtraction
2nd Grade Math » Unit: The Action of Subtraction
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

The big idea of this lesson is that addition and subtraction facts are related, and every subtraction fact has a related addition fact. Students can think of this inverse relationship when recalling basic subtraction facts.

 
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Resources (16)
 
Reflections (1)
screen shot 2013 12 19 at 2 45 55 pm
   

More Than Two Numbers

2nd Grade Math » Unit: The Mission of Addition
2nd Grade Math » Unit: The Mission of Addition
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

The big idea of this lesson is that three (or more) numbers can be grouped together and added. The order of this grouping doesn't matter.

 
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Resources (12)
 
Reflections (1)
prev800p1
   

Think About Related Addition Facts to 10

2nd Grade Math » Unit: The Action of Subtraction
2nd Grade Math » Unit: The Action of Subtraction
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

Students can use their knowledge of using addition to make ten to help them find the related subtraction fact.

 
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Resources (14)
 
Reflections (1)
screen shot 2013 12 19 at 2 11 00 pm
   

Go Fishing for Doubles

2nd Grade Math » Unit: The Mission of Addition
2nd Grade Math » Unit: The Mission of Addition
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

Students play a favorite card game which practices the quick and accurate recall of double facts.

 
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Reflections (1)
happy boy with glasses on fishing proudly holding a fish catch
   

Think About Adding Nothing and a Little More

2nd Grade Math » Unit: The Mission of Addition
2nd Grade Math » Unit: The Mission of Addition
Kristen O'Connor
Pepperell, MA
Environment: Rural
 
Big Idea:

The big idea of this lesson is the understanding that the number relationships between 0 more than, 1 more than, and 2 more than lay the foundation for the basic addition facts with 0, 1, and 2.

 
Favorites (6)
 
Resources (16)
 
Reflections (1)
256px linking cm cubes 2
   

Counting Bugs

2nd Grade Math » Unit: Adding and Subtracting the Basics
2nd Grade Math » Unit: Adding and Subtracting the Basics
Beth McKenna
York, ME
Environment: Suburban
 
Big Idea:

Students need to experience real life math situations. They also need to become comfortable sharing their understandings with others.

 
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Resources (10)
 
Reflections (1)
biedrona
   

Doubles Plus or Minus One

2nd Grade Math » Unit: Adding and Subtracting the Basics
2nd Grade Math » Unit: Adding and Subtracting the Basics
Beth McKenna
York, ME
Environment: Suburban
 
Big Idea:

One of the Four Critical Areas of 2nd grade math is the application of understanding of models for addition and subtraction. An efficient way to do this is to develop strategies built on what students know.

 
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Resources (13)
 
Reflections (1)
100 0582
   

Let Me Count The Ways to Get An Answer

2nd Grade Math » Unit: Adding and Subtracting the Basics
2nd Grade Math » Unit: Adding and Subtracting the Basics
Beth McKenna
York, ME
Environment: Suburban
 
Big Idea:

One Common Core goal for second grade is the ability to use place value in the addition and subtraction of numbers to 100. This lesson is a foundation for this skill.

 
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Resources (9)
 
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duck
   

How do I solve a change unknown word problem?

2nd Grade Math » Unit: Three-Digit Addition and Subtraction
2nd Grade Math » Unit: Three-Digit Addition and Subtraction
Caitlin Vaughan
Environment: Urban
 
Big Idea:

This lessons starts with a concrete representation of a change unknown problem and then pushes students to think abstractly and develop number sentences to solve change unknown word problems.

 
Favorites (7)
 
Resources (20)
 
Reflections (1)
img 0515
Common Core Math
 
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