Adding Two 2-Digit Numbers on a Number Line

The video tutorial demonstrates how to add two two-digit numbers using an open number line. It explains the flexibility of this method and provides multiple examples of adding 43 and 25 using different strategies. The tutorial emphasizes that students can choose their own approach, whether starting with the higher or lower number, and breaking numbers into parts that suit their comfort level.

What is the purpose of using an open number line in addition?

• To limit the number of steps in addition

• To provide a pre-numbered line for easy calculation

• To offer flexibility in choosing starting points and increments

• To complicate simple addition problems

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CCSS.1.OA.A.1

How is the number 25 added to 43 in the first example?

• In increments of 20, 5

• As a whole without breaking it down

• In increments of 30, -5

• In increments of 10, 10, and 5

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CCSS.1.NBT.C.4

CCSS.2.MD.B.6

What is the final sum of 43 and 25 in the first example?

• 63

• 68

• 53

• 88

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CCSS.1.NBT.C.4

CCSS.2.NBT.B.5

In the second example, what increments are used to add 25 to 43?

• 15, 10

• 25 as a whole

• 20, 5

• 10, 10, 5

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CCSS.1.NBT.C.4

CCSS.2.MD.B.6

What demonstrates the flexibility of the open number line method?

• Starting with the larger number

• Choosing different starting points and increments

• Using only large increments

• Adding numbers in descending order

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CCSS.1.NBT.C.4

CCSS.2.MD.B.6

When starting with 25, what is the first increment used to reach 43?

• 18

• 10

• 20

• 15

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CCSS.1.NBT.C.5

What is the total sum when starting with 25 and adding 43?

• 70

• 75

• 65

• 68

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CCSS.1.NBT.C.4

CCSS.2.NBT.B.5

How many different ways are demonstrated for adding 43 and 25?

• Three ways

• Two ways

• Four ways

• One way

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CCSS.1.NBT.C.4

CCSS.2.NBT.B.5

What is the sum of 43 and 25 when using the open number line?

• 68

• 75

• 80

• 85

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CCSS.1.NBT.C.4

CCSS.2.MD.B.6

Which of the following is not a correct representation of adding 43 and 25?

• 43 + 25 = 68

• 43 + 25 = 75

• 25 + 43 = 68

• 43 + 20 + 5 = 68

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CCSS.1.NBT.C.4

CCSS.2.NBT.B.5