Videos and songs to help Grade 2 students learn how to fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.

Common Core: 2.OA.2

### Suggested Learning Target

• 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)

Related Topics:

In these lessons, 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.

Doubles and Near 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.

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.