Download Math-Module-2-Lesson-4

Module 2 Lesson 4
Convert numerical expressions into unit form as a
mental strategy for multi-digit multiplication.
Stephen J. O’Connor
[email protected]
ccss5.com
Based upon lessons created by Common Core, Inc
Common Core
Standards
5.OA.2 Write simple expressions that record calculations with
numbers, and interpret numerical expressions without evaluating
them. For example, express the calculation “add 8 and 7, then
multiply by 2” as 2 × (8 + 7). Recognize that 3 × (18932 + 921) is
three times as large as 18932 + 921, without having to calculate
the indicated sum or product.
5.NBT.5 Fluently multiply multi-digit whole numbers using the
standard algorithm.
Learning Targets
• I can convert numerical expressions
into unit form as a mental strategy for
multi-digit multiplication.
Activate
Knowledge
Estimate the product
409 × 21 ≈ ____ × ___ = ___
Activate
Knowledge
Estimate the product
287 × 64 ≈ ____ × ___ = ___
Activate
Knowledge
Estimate the product
3,875 × 92 ≈ ____ × ___ = ___
Activate
Knowledge
Estimate the product
6,130 × 37 ≈ ____ × ___ = ___
Activate
Knowledge
Write the multiplication sentence
12 × 3 =___
Activate
Knowledge
Write the multiplication sentence
12 × 3 =___
12 is the same as 8 and what number?
(8 × 3) + ( __ × 3) = ____
Activate
Knowledge
Write the multiplication sentence
12 × 3 =___
12 is the same as 8 and what number?
(8 × 3) + ( __ × 3) = ____
24 + ____ = ____
Activate
Knowledge
Write the multiplication sentence
14 × 4 =___
Activate
Knowledge
Write the multiplication sentence
14 × 4 =___
14 is the same as 10 and what number?
(10 × 4) + ( __ × 4) = ____
Activate
Knowledge
Write the multiplication sentence
14 × 4 =___
14 is the same as 10 and what number?
(10 × 4) + ( __ × 4) = ____
40 + ____ = ____
Activate
Knowledge
Write the multiplication sentence
13 × 3 =___
Activate
Knowledge
Write the multiplication sentence
13 × 3 =___
13 is the same as 10 and what number?
(10 × 3) + ( __ × 3) = ____
Activate
Knowledge
Write the multiplication sentence
13 × 3 =___
13 is the same as 10 and what number?
(10 × 3) + ( __ × 3) = ____
30 + ____ = ____
Activate
Knowledge
Write the multiplication sentence
15 × 6 =___
Activate
Knowledge
Write the multiplication sentence
15 × 6 =___
15 is the same as 10 and what number?
(10 × 6) + ( __ × 6) = ____
Activate
Knowledge
Write the multiplication sentence
15 × 6 =___
15 is the same as 10 and what number?
(10 × 6) + ( __ × 6) = ____
60 + ____ = ____
Activate
Knowledge
Write expression as a single multiplication
sentence without brackets
11 × (15 + 5)
Activate
Knowledge
Write expression as a single multiplication
sentence without brackets
(41 – 11) × 12
Activate
Knowledge
Write expression as a single multiplication
sentence without brackets
(75 + 25) × 38
Activate
Knowledge
Write expression as a single multiplication
sentence without brackets
(20 × 2) + (6 × 2)
Activate
Knowledge
Jaxon earned $39 raking leaves. His brother,
Dayawn, earned 7 times as much waiting on
tables. Write a numerical expression to show
Dayawn’s earnings. How much money did
Dayawn earn?
Learn
What does this expression mean
when I designate 31 as the unit?
8 × 31
Problem 1
Learn
Does our choice of unit change the
product of the two factors?
8 × 31
Problem 1
Learn
Let’s designate 8 as the unit.
31 eights
8
8
8 …
8 8 8 …
8
8
30 eights
Problem 1
Learn
What does this expression mean
when I designate 8 as the unit?
8 × 29
Problem 2
Learn
Let’s designate 8 as the unit.
30 eights
8
8
8 …
8 8 8 …
8
8
29 eights
Problem 2
Learn
Is 49 twenties or 20 forty-nines
easier to work with?
49 × 20
Problem 3
Learn
Let’s designate 20 as the unit.
50 twenties
20 20 20 …
20
Problem 3
Learn
Let’s designate 20 as the unit.
49 twenties
40 twenties
9 twenties
Problem 3
Learn
Let’s designate 20 as the unit.
49 twenties
40 twenties
9 twenties
Problem 3
Learn
Let’s designate 20 as the unit.
20 × 51
Problem 4
✔
Check
Understanding
101 x 12
Problem 5
✔
Check
Understanding
12 × 98
Problem 6
Practice
Review