# Operations & Algebraic Thinking

**Operations &Algebraic Thinking (OA)**

Represent and solve problems involving addition and subtraction.

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}

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.

Understand and apply properties of operations and the relationship between addition and subtraction.

Apply properties of operations as strategies to add and subtract.^{2} *Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)*

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

Add and subtract within 20.

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

Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (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).

Work with addition and subtraction equations.

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.

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 = _*.

**Operations & Algebraic Thinking (OA) 1.OA.1**

**1.OA.A.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.

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Do these activities: **KHAN ACADEMY 1.OA.A.1 ACTIVITY 1 - Addition and Subtraction Word Problems 1**

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Do these activities: **KHAN ACADEMY 1.OA.A.1 ACTIVITY 4 - Word Problems With "More" and "Fewer" 1**

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**Operations & Algebraic Thinking (OA)**

**1.OA.A1**

**IXL Activities**

Word problems - write the addition sentence (First grade - B.5)

Subtraction with pictures - numbers up to 10 (First grade - D.1)

Subtraction sentences - numbers up to 10 (First grade - D.2)

Subtraction word problems - one-digit numbers (First grade - D.4)

Word problems - write the subtraction sentence (First grade - D.5)

Subtraction word problems - numbers up to 18 (First grade - D.14)

Customary units of length: word problems (First grade - N.6)

**Operations & Algebraic Thinking (OA) 1.OA.2**

**1.OA.A.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.

**Watch This Video**

**Operations & Algebraic Thinking (OA)**

**1.OA.A2**

**IXL Activities**

**Operations & Algebraic Thinking (OA) 1.OA.3**

**1.OA.B.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, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)

**Watch This Video**

Videos for this standard are **coming soon** to Khan Academy.

**Fact Triangle**

**Fact Family**

3 + 4 = 7

4 + 3 = 7

7 â€“ 4 = 3

7 â€“ 3 = 4

Do these activities: **KHAN ACADEMY 1.OA.B.3 ACTIVITIES (Coming Soon)**

**Operations & Algebraic Thinking (OA)**

**1.OA.B3**

**IXL Activities**

**Adding three numbers (First grade - B.17)**

**Word problems - adding three numbers (First grade - B.18)**

**Related addition facts (First grade - B.19)**

**Operations & Algebraic Thinking (OA) 1.OA.4**

**1.OA.B.4**

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

**Watch This Video**

**Relating addition and subtraction | Basic addition and subtraction | Early Math | Khan Academy**

**Operations & Algebraic Thinking (OA)**

**1.OA.B4**

**IXL Activities**

**Operations & Algebraic Thinking (OA) 1.OA.5**

**1.OA.C.5**

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

**Khan Academy: **Add and subtract within 20.

**Watch This Video**

Skills for this standard are **coming soon** to Khan Academy.

Do these activities: **KHAN ACADEMY 1.OA.C.5 ACTIVITIES (Coming Soon)**

**Operations & Algebraic Thinking (OA)**

**1.OA.C5**

**IXL Activities**

**Operations & Algebraic Thinking (OA) 1.OA.6**

**1.OA.6**

Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 â€“ 4 = 13 â€“ 3 â€“ 1 = 10 â€“ 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 â€“ 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).

**Watch This Video**

**Addition and Subtraction Within 20 | Early Math | Khan Academy**

**Operations & Algebraic Thinking (OA)**

**1.OA.C6**

**IXL Activities**

Ways to make a number - addition sentences (First grade - B.7)

Addition sentences to 18 using number lines (First grade - B.13)

Ways to make a number - subtraction sentences (First grade - D.7)

Ways to subtract from a number - subtraction sentences (First grade - D.8)

Subtraction sentences within 18 using number lines (First grade - D.12)

Subtract one-digit numbers from two-digit numbers (First grade - D.20)

Addition and subtraction - ways to make a number (First grade - F.1)

Addition and subtraction facts - numbers up to 10 (First grade - F.4)

Addition and subtraction facts - numbers up to 18 (First grade - F.5)

**Operations & Algebraic Thinking (OA) 1.OA.7**

**1.OA.D.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 â€“ 1, 5 + 2 = 2 + 5, 4 + 1 = 5 + 2.

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**Operations & Algebraic Thinking (OA)**

**1.OA.D7**

**IXL Activities**

**Operations & Algebraic Thinking (OA) 1.OA.8**

**1.OA.D.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 = ? â€“ 3, 6 + 6 = ?.

**Watch This Video**

**Operations & Algebraic Thinking (OA)**

**1.OA.D8**

**IXL Activities**

**Operations and Algebraic Thinking (OA) Games**

Represent and solve problems involving addition and subtraction.

Understand and apply properties of operations and the relationship between addition and subtraction.

Add and subtract within 20.

Work with addition and subtraction equations.

**Addition Games**

**Number Bonds 10 (Easy)**

Combine number balls to make **sums of 10.**

**Number Bonds 20 (Medium)**

Combine number balls to make **sums of 20.**

**Number Bonds 30 (Medium-Challenging) **Combine number balls to make **sums of 30.**

**Number Bonds 40 (Challenging)**

Combine number balls to make **sums of 40.**

**Alien Addition**

Practice sums and addition facts in this exciting math game.

**Jet Ski Addition**

Practice **sums within 20** and **addition facts**.

**Tug Team Addition**

Practice **sums within 20** and **addition facts** with this fun-filled math game.

**Math Monster Addition**

Choose one or more addends. Can you make all 12 monster friends appear?

**Zogs and Monsters Addition**

Move the friendly zogs to the correct sums without being captured.

**Puzzle Pics Addition**

Choose a target **sum (10 to 20) **to practice. Place the puzzle piece on the number in the grid.

**Kitten Match Addition**

Practice **sums of 10**and **addition facts** by clicking two fur balls that make 10.

**Canoe Puppies Addition (Challenging)**

Add two-digit numbers correctly to win the race.

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**Subtraction Games**

**Island Chase**

Practice **subtraction** facts (**within 20**) with a fun math game in a tropical setting.

**Sailboat Tug**

Practice **subtraction** facts (**within 20**) with a fun math game in a tropical setting.

**Math Monster Subtraction**

Choose one or more numbers to subtract. Can you make all 12 monster friends appear?

**Ducky Race Subtraction (Challenging)**

Practice subtraction facts in a duck racing math game. (**Positive** and **Negative **Numbers)

**Minus Mission (Challenging)**

Practice **subtraction** facts with a space-themed math game.

**Puzzle Pics Subtraction** Choose the largest starting number (**10 to 20**). Place the puzzle piece on the missing number in the grid.