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- The Original Triangle Flash Cards: Addition & Subtraction

## The Original Triangle Flash Cards: Addition & Subtraction

**SKU:**

### Description

*Triangle Flash Cards*teach families of facts, showing the relationship between addition and subtraction. How is 4 in one corner related to 7 and 3 in the other corners? Cover the sum, in red, and practice addition: 4 + 3 = 7 or 3 + 4 = 7. Cover one of the addends, in black, and practice subtraction: 7 – 4 = 3 or 7 – 3 = 4. A total of 20 cards aid mastery of 160 math facts up to 9 + 9 and 18 - 9. Also available for multiplication and division. For 2 or more players.

**WCA 4551 Addition & Subtraction**

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4551 Triangle Flash Cards Add/Sub

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 – 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.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 = _.