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Common Core: 2.OA.2

- I can use mental strategies (e.g., count on, make a ten) to add or subtract numbers within 20 with ease.
- I can recall from memory all sums of two one-digit numbers.
- I can apply counting strategies.
- I can use reasoning strategies to make use of known facts (e.g., sums of ten, making ten, doubles, near doubles/inside doubles, doubles plus, counting on)
- I know that subtraction is the inverse of addition (e.g., fact families)

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More Lessons for Grade 2

Common Core for Grade 2

In this lesson, we will review some of the math strategies that can be used for addition and subtraction.

Add 1, 2, 3 to 1-digit number

This video explains the addition strategy for adding 1, 2, and 3 to any number by counting on.

Addition Properties

In this video, you will learn about addition properties including the commutative property of addition, the zero property of addition, and the associative property of addition.

Addition Doubles Rock

Add 1, 2, 3 to 1-digit number

This video explains the addition strategy for adding 1, 2, and 3 to any number by counting on.

In this video, you will learn about addition properties including the commutative property of addition, the zero property of addition, and the associative property of addition.

Doubles and Near Doubles

Addition Strategy (Doubles)

Mental Math Strategies: Make 10

This video shows how to use mental strategies to add within 20 using the "make 10" strategy. This is one of the strategies suggested in the Common Core State Standards for Mathematics, 1.OA.6 and 2.OA.2.

With practice, this strategy can help students gain fluency when adding within 20. Eventually students will memorize these facts, which is expected by the end of grade 2.

Make 10 Strategy for Addition

Step 1: The first addend and what make ten?

Step 2: Write the number below the second addend?

Step 3: The number below the second addend and what make the scond addend?

Step 4: Add the rest to 10

Addition Strategy (Doubles)

This video shows how to use mental strategies to add within 20 using the "make 10" strategy. This is one of the strategies suggested in the Common Core State Standards for Mathematics, 1.OA.6 and 2.OA.2.

With practice, this strategy can help students gain fluency when adding within 20. Eventually students will memorize these facts, which is expected by the end of grade 2.

Step 1: The first addend and what make ten?

Step 2: Write the number below the second addend?

Step 3: The number below the second addend and what make the scond addend?

Step 4: Add the rest to 10

Mental Math Strategies: Break Down to 10

This video explains how to use mental strategies to subtract within 20 using the "break down to 10" strategy.

Mental Math Strategies: Addition & Subtraction Relationship

This video explains how to use mental strategies to add and subtract within 20 using the relationship between addition and subtraction.

Mental Math Strategies: Use Known Equivalent Sums

This video explains how to use mental strategies to add within 20 using known sums to solve unknown sums.

This video explains how to use mental strategies to subtract within 20 using the "break down to 10" strategy.

This video explains how to use mental strategies to add and subtract within 20 using the relationship between addition and subtraction.

This video explains how to use mental strategies to add within 20 using known sums to solve unknown sums.

Compensation Strategy for Addition

This video shows the compensation strategy for addition modeled concretely and using number bonds.

The Arrow Way Addition

This video demonstrates the written recording method know as "the arrow way."

This video shows the compensation strategy for addition modeled concretely and using number bonds.

This video demonstrates the written recording method know as "the arrow way."