G5 10/15 Unit 5 and 6 Review

Find the Mistake

100

150 ÷ 12 = 12

What mistake did they make?

Answer: They forgot place value.

The student forgot the remainder.

Correct answer:

150 ÷ 12 = 12 R6

200

48 ÷ 14 = 4

What mistake did the student make?

The student chose a quotient that is too large.

4 × 14 = 56

and 56 is greater than 48.

48 ÷ 14 = 3 R6

300

A student checked their division problem and showed:

Plain Text

2335 ÷ 11 = 212 R3

 

11 × 212 = 2332

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The student concluded:

"My answer is correct because I used multiplication to check it."

Question

Do you agree with the student? Explain the mistake and describe what should have happened instead.

The student forgot to add the remainder.

A proper check would be:

11 × 212 = 2332

2332 + 3 = 2335

(Quotient × Divisor) + Remainder = Dividend

Mission Control Procedures (DMSCB)

100

What does the C in DMSCB stand for?

Compare

200

A student used the steps:

Divide

Multiply

Subtract

Bring Down

Compare

What is wrong?

Compare should happen before Bring Down.

Divide

Multiply

Subtract

Compare

Bring Down

Mission Verification (Inverse Operations)

100

95 × 14 = 1330

Which division equation does this verify?

1330 ÷ 14 = 95

1330 ÷ 95 = 14

200

Complete the formula:

(Quotient × Divisor) + ______ = Dividend

Remainder

300

A student claims: 

3277 ÷ 31 = 99 R2

99 × 31 = 3069

3069 + 2 = 3071

Is the student's answer correct? Convince me.

No.

The check equals:

3071

but the dividend is:

3277

The answer does not check.

Mission Strategy & Reasoning

100

Estimate: 710 ÷ 9

A student chooses: 700 ÷ 9

A second student chooses:  720 ÷ 9

Which estimate is better and why?

720 ÷ 9 

because 720 is compatible with 9 and is easier to divide mentally.

200

Which number is the dividend?

648 ÷ 8

648

The dividend is the number being divided.

300

Convince Me:

Why is estimating before solving a problem helpful?

• It helps determine if the final answer is reasonable.

• It helps catch mistakes.

• It helps predict approximately what the answer should be.

• It helps decide whether a final answer is too large or too small.

⭐ FINAL JEOPARDY

300

FINAL JEOPARDY:

A spacecraft has collected 12,308 units of fuel.

The fuel must be divided equally among 15 storage tanks.

A student claims:  12,308 ÷ 15 = 820 R8

In Breakout Rooms Your team must:

Part 1

Determine whether the answer is correct.

Part 2

Show how to check the answer.

Part 3

Convince Mission Control that your conclusion is correct.

Check:

820 × 15 = 12,300

Add the remainder:

12,300 + 8 = 12,308

The check equals the dividend.

12,308 ÷ 15 = 820 R8

is correct.

Convince Me Response:

We know the answer is correct because multiplying the quotient by the divisor and adding the remainder recreated the original dividend. Since 12,300 + 8 = 12,308, the division equation is true. 🚀