Videos to help Grade 5 students learn how to convert numerical expressions into unit form as a mental strategy for multi-digit multiplication.

Common Core Standards: 5.OA.1, 5.OA.2, 5.NBT.5

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Lesson Plans and Worksheets for Grade 5

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Common Core For Grade 5

New York State Common Core Math Module 2, Grade 5, Lesson 4

Lesson 4 Concept Development

Problems 1–2

8 × 31

8 × 29

Problems 3–4

49 × 20

20 × 51

Problems 5–6

101 × 12

12 × 98

Lesson 4 Problem Set

1. Circle each expression that is not equivalent to the expression in bold.

a.

29 sixteens

16 × (30 – 1)

(15 – 1) × 29

(10 × 29) – (6 × 29)

b.

(38 + 40) × (38 + 5)

(38 × 40) + (38 × 5)

45 × (40 + 2)

45 thirty-eights

2. Solve using mental math. Draw a tape diagram and fill in the blanks to show your thinking.

c. 79 × 14 = _____ fourteens

Think: ____ fourteens – 1 fourteen

= (____ × 14) – (___ × 14)

= ______ - ______ = ______.

d. 21 × 75 = ____ seventy-fives

Think: ___ seventy-fives + ___ seventy-five

= (___ × 75) + (___ × 75)

= ______ + ______ = _____

3. Define the unit in word form and complete the sequence of problems as was done in Problems 3–4 in the lesson.

a. 19 × 15 = 19 __________

Think: 20 _______ – 1 __________

= (20 × ____) – (1 × ___)

= _______ – _______ = _______

b. 14 × 15 = 14 ________

Think: 10 _________ + 4 _________

= (10 × ____) + (4 × _____)

= _______ + _______ = _______

Lesson 4 Homework

1. Circle each expression that is not equivalent to the expression in bold.

a. 37 × 19

37 nineteens

(30 × 19) – (7 × 29)

37 × (20 – 1)

(40 – 2) × 19

2. Solve using mental math. Draw a tape diagram and fill in the blanks to show your thinking.

b. 11 × 26 = ________ twenty-sixes

Think: _______ twenty-sixes + ____ twenty-sixes

= (_____ × 26) + (_____ × 26)

= __________ + __________ = _________

3. Define the unit in word form and complete the sequence of problems.

c. 19 × 11 = 19 ____________________

Think: 20 ________ – 1 ________

= (20 × ______) – (1 × _____)

= __________ – __________ = __________

This video demonstrates how to use mental math to evaluate expressions involving multiplication.

3. Define the unit in word form and complete the sequence of problems.

a. 29 × 12 = 29 ____________________

Think: 30 _____________ – 1 _____________

= 30 × ______) – (1 × _____)

= __________ – __________ = __________

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