Long Division: Using Standard Algorithm Adapted from 21 st Century Lessons 1

Long Division: Using Standard Algorithm

Adapted from 21st Century Lessons

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Objectives

• Students will be able to indentify the parts of division problems in various forms.

• Students will be able to explain and apply multi-digit division using standard algorithm.

• Students will be able to discuss long division using correct vocabulary.

Vocabulary

• Algorithm: A formula or set of steps for solving a problem.

• Division: Splitting of large numbers into equal groups of smaller numbers.

• Dividend: Number being divided.• Divisor: Number you are dividing by.• Quotient: Answer to a division problem.

Vocabulary Video

http://youtube.com/watch?v=0RCjWZe0qBQ

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On a school field trip, your class followed a treasure map and found a buried treasure! Imagine that your class has 25 students total, and that there were 1000 gold coins in the treasure chest.How many coins

does each student get? Express your answer in three different ways.

Warm Up

Warm Up

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Express the problem in three ways.

We found 1000 gold coins, and need to divide them equally between the 25 students in our class.

_____ 25) 1000 1000 =

251000 ÷ 25 =

Warm Up

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So how many coins does each student get?

_____ 25) 1000 1000 =

251000 ÷ 25 =

We’ll check back on this problem in a little while!

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With your partner, list the three ways to express the clam’s division problem.

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With your partner, list the three ways to express the clam’s division problem:

FRACTION LONG DIVISION ALGORITHM

NUMBER SENTENCE

The Steps to Long Division Video

http://www.youtube.com/watch?v=0uZiqk_ZdcA

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How many steps are there in the long division algorithm?

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How many steps are there?

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Let’s apply the steps to long division to a new problem:

84 ÷ 6 = ?

Explore

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DIVIDE

MULTIPLY

SUBTRACT

BRING DOWN

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Set up the problem: 84 ÷ 6 = ? in the long division algorithm looks like which of the options below?

84 ? ) 6

84 = ? 6

84 6 ) ?

6 = ? 84

? 6) 84

84 = ? 6

CHOICE A CHOICE B CHOICE C

✗ ✗

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8 ÷ 6 =

STEP ONE: DIVIDE

We divide the dividend by the divisor.

1Follow along with the Guided Practice Worksheet!

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6 x 1 =

STEP TWO: MULTIPLY

We multiply

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6

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STEP FOUR: BRING DOWN

We bring the 4 down

4

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8 – 6 =

STEP THREE: SUBTRACT

We subtract

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NOW WHAT???

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24 ÷ 6 =

STEP ONE: DIVIDE

We divide

4

4

22

6 X 4 =

STEP TWO: MULTIPLY

We multiply

242 4

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24 – 24 =

STEP THREE: SUBTRACT

We subtract

00

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STEP FOUR: BRING DOWN

There is no number to bring down – we’re almost DONE!

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Don’t forget to check your answer!

The opposite of 84 ÷ 6 = 14 is

6 X 14 =

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Checking your answer

84

14x 6

Practice 1

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Let’s try one more problem – try it alone and we’ll review it together!

What do these number sentences look like in the long division algorithm?

? 12) 144

144 ÷ 12 = ? 14412 = ?

Practice 1

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14 ÷ 12 =

STEP ONE: DIVIDE

What are we dividing?

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We are dividing the dividend by the divisor.

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Practice 1

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12 X 1 =

STEP TWO: MULTIPLY

We multiply12

12

Practice 1

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14 – 12 =

STEP THREE: SUBTRACT

We subtract 22

Practice 1

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STEP FOUR: BRING DOWN

We bring down

4

Practice 1

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NOW WHAT???

Practice 1

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24 ÷ 12 =

STEP ONE: DIVIDE

We divide the dividend by the divisor.

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2

Practice 1

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12 x 2 =

STEP TWO: MULTIPLY

We multiply 2424

Practice 1

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24 - 24 =

STEP THREE: SUBTRACT

We subtract 0

0

Practice 1

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STEP FOUR: BRING DOWN

There is no number to bring down – we’re almost done!

Practice 1

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Don’t forget to check your answer!

The opposite of 144 ÷ 12 = 12 is

12 X 12 =

Practice 1

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Checking your answer

144

12x 12

Exit Ticket

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So how many coins does each student get?

_____ 25) 1000 1000 =

251000 ÷ 25 =

Show your work using the long division algorithm.

Exit Ticket

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So how many coins does each student get?

Each student gets gold

coins!40

Summary

1. How many steps are there to the long division algorithm? What are they?

2. What is the trick the video taught us to remember the steps?

3. Is there anything confusing about usingthe long division algorithm?

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Credits

Original lesson designed by Catherine Murphy & Sarah Kelly. 21st Century Lessons. Funded by the American Federation of Teachers. Retrieved from http://www.sharemylesson.com