This is an introduction to the addition, subtraction, multiplication, and division strategies used in 3rd grade.

1. Math Strategies
in Third Grade
Presented by Dawn Rosevear

2. What’s
the
Big
Deal?

3. Well Rounded Mathematicians
Conceptual
Understanding
Procedural
Skills and
Fluency
Application

4. 3rd Grade Expectations
● Solve single and multi-step word problems
● Master a number of addition, subtraction,
multiplication, and division strategies
● Be able to select the strategy that works best for
them
● Select the most efficient strategy for the problem
● Check their work with another strategy
● Understand the relationship between the operations
● Explain their thinking verbally and in writing

5. Making Connection s
“Each standard is not a new event, but an
extension of previous learning.”
-Common Core Standards

6. Addition and Subtraction Strategies
Standard Algorithm Expanded Form
4,235
+ 3,652
________
7,887
4,000+200+30+5
+ 3,000+600+50+2
____________
7,000+800+80+7

7. Addition and Subtraction Strategies
Keep One Break One
Base Ten Blocks
456+231=
456+200=656
656+30=686
686+1=687

8. Addition and Subtraction Strategies
Number Line
345+125=
345 445 465 470
Bar Model
+100
+20 +5
?
whole
345 125
part
part
345+125=___

9. Multiplication and Division Strategies
Equal Groups
Phyllis was feeling festive and made
autumnal cookies for her friends. She baked
21 cookies. She is putting an equal number of
cookies in 3 bags. How many cookies will be in
each bag?
Array
Ms. Golub has 16 keyboards. She arranges
them in 4 equal rows. How many keyboards
are in each row?
21 ÷ 3 = 7
16÷4=4
4x4=16

10. Multiplication and Division Strategies
Repeated Addition
3X8=
8+8+8=
3+3+3+3+3+3+3+3=
Repeated Subtraction
Subtract until you get to zero!
24÷8=
24-8=16
16-8=8
8-8=0

11. Bar Model
Mr. Nichols got 3 shipments of 12
bicycles each. How many bicycles
was Mr. Nichols shipped?
If Mr. Nichols stores all bicycles he
was shipped in rows of 6, how
many bicycles would be in each
row?
What strategy would work best to
solve this problem?
?
12 12 12
An Array!

12. The Principal Properties
Property Multiplication/Division Addition/Subtraction
Commutative axb=bxa
3x2=2x3
a+b=b+a
5+4=4+5
Associative (axb)xc=ax(bxc)
(3x4)x5=3x(4x5)
12x5=60 20x3=60
(2+3)+4=2+(3+4)
5+4=9 2+7=9
Distributive ax(b+c)=axb+axc
2x(4+6)=2X4+2X6
2x10=20 8+12=20

13. Hot Seat: Your Turn to Try
What strategy
would work
best for this
problem?
If 18 Halloween treats are
shared equally into 3 bags,
then how many treats will
be in each bag?

14. Hot Seat: Your Turn to Try
What strategy
would work
best for this
problem?
Mr. Bender picked 24
apples from Stoneledge
Farm. If he arranges the
apples into 3 equal rows,
how many apples will be
in each row?

15. Enrichment
Opportunities
MoMath
The Museum of
Mathematics
11 East 26th Street
Video
Resources
Khan Academy
Learnzillion
Show Me