Unit 3

Operations of Algebraic Thinking

 

Grade 1

Math

Unit Length and Description:

 

6 Weeks

 

This unit focuses on using different strategies to add and subtract within 20, on applying properties of operations to addition and subtraction, and on the meaning of the equal sign. The development of fluency for addition and subtraction within 10 continues to be a focus.

 

Standards:

 

CCSS for Mathematical Content

CCSS #

CCSS Text

Operations and Algebraic Thinking

1.OA.1

Use addition and subtraction within 20 to solve word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.

1.OA.2

Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.

1.OA.3

Apply properties of operations as strategies to add and subtract.  Examples:  If 8 + 3 = 11 is known, then 3 + 8 =11 is also known.  (Commutative property of addition.)  To add 2 + 6 + 4 = 2 + 10 = 12.  (Associative property of addition.)

1.OA.4

Understand subtraction as an unknown-addend problem.  For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.

1.OA.5

Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).

1.OA.6

Add and subtract within 20, demonstrating fluency for addition and subtraction within 10.  Use strategies such as counting on; making 10 (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 =4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 +1 = 12 + 1 = 13).

1.OA.7

Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false.  For example, which of the following equations are true and which are false? 6 = 6, 7 = 8 – 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.

1.OA.8

Determine the unknown whole number in an addition or subtraction equation relating three whole numbers.  For example, determine the unknown number that make the equation true in each of the equations 8 + ? = 11, 5 = ___ – 3, 6 + 6 = ___

Standards for Mathematical Practice (MP)

MP.2

Reason abstractly and quantitatively.

MP.7

Look for and make use of structure.

MP.8

Look for and express regularity in repeated reasoning.

CCSS for ELA Content

CCSS#

CCSS Text

Writing

W.1.8

With guidance and support from adults, recall information from experiences or gather information from provided sources to answer a question.

Speaking and Listening

SL.1.1

Participate in collaborative conversations with diverse partners about grade 1 topics and texts with peers and adults in small and larger groups.

a. Follow agreed-upon rules for discussion (e.g., listening to others with care, speaking one at a time about the topics and texts under discussion).

b. Build on others’ talk in conversations by responding to the comments of others through multiple exchanges.

c. Ask questions to clear up any confusion about the topics and texts under discussion.

Instructional Outcomes

1.OA.1: Use addition and subtraction within 20 to solve word problems involving situations of adding to, take from, putting together, taking apart, and comparing, with unknowns in all positions, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.

  • I can use a symbol (e.g. ?, x) to represent an unknown number in a problem.
  • I can determine the operation to solve word problems with unknowns.
  • I can use different strategies for addition to solve word problems within 20.
  • I can use different strategies for subtraction to solve word problems within 20.
  • I can solve word problems by adding 3 numbers in different ways.

 

1.OA.2: Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20, e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.

·        I can add 3 numbers.

·        I can identify parts/addends in a word problem.

·        I can show how to solve word problems

 

1.OA.3: Apply properties of operations as strategies to add and subtract.  Examples:  If 8 + 3 = 11 is known, then 3 + 8 =11 is also known.  (Commutative property of addition.)  To add 2 + 6 + 4 = 2 + 10 = 12.  (Associative property of addition.)

  • I can use fact families to help me solve addition problems. (commutative)
  • I can explain how properties of addition and subtraction work.
  • I can use strategies to solve addition and subtraction problems.

 

1.OA.4: Understand subtraction as an unknown-addend problem.  For example, subtract 10 – 8 by finding the number that makes 10 when added to 8.

·        I can identify the unknown in a subtraction problem.

·        I can solve subtraction problems to find the missing addend.

·        I can explain the relationship of addition and subtraction.

 

1. OA.5: Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).

  • I can count on from a given number.
  • I can count back from a given number.
  • I can explain how counting on relates to addition.
  • I can explain how counting back relates to subtraction.
  • I can explain how counting on relates to subtraction.

 

1.OA.6: Add and subtract within 20, demonstrating fluency for addition and subtraction within 10.  Use strategies such as counting on; making 10 (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4 = 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 =4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 +1 = 12 + 1 = 13).

  • I can add within 20.
  • I can subtract within 20.
  • I can use strategies to add and subtract within 20.
  • I can add fluently within 10.
  • I can subtract fluently within 10.

 

1.OA.7: Understand the meaning of the equal sign, and determine if equations involving addition and subtraction are true or false.  For example, which of the following equations are true and which are false? 6 = 6, 7 = 8 – 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.

·        I can explain the meaning of an equal sign.

·        I can compare the values on each side on an equal sign.

·        I can determine if the equation is true or false.

 

1.OA.8: Determine the unknown whole number in an addition or subtraction equation relating three whole numbers. For example, determine the unknown number that makes the equation true in each of the equations 8 + ? = 11, 5 = _ – 3, 6 + 6 = _.

  • I can recognize part-part-whole relationships of three numbers
  • I can figure out the missing value in an addition equation.
  • I can figure out the missing value in a subtraction problem.

 

Enduring Understandings:

 

Students will understand that an equal sign in an equation means that both sides of the equation have the same value.  Students will determine if equations are true or false.  Students will add and subtract within 20 using various strategies.

Essential Questions:

 

·        How can we show and explain our thinking?

·        How do strategies help me add and subtract?

·        How can I tell about a number in different ways?

·        How do I know when to add or when to subtract?