1. Arrays and Using an Expanded Algorithm
Literature Link: The Grapes of Math by Greg Tang (1-2 pages)
Lesson 6-1
CCSS 4.NBT.5

2. MATH Essential Questions
How do I know which computational
method (mental math, estimation, paper and
pencil, and calculator) to use?
MATH
Essential
Questions

3. MATH Essential Questions
How do mathematical operations relate to
each other?
MATH
Essential
Questions

4. MATH Essential Questions
Why do I need mathematical operations?
MATH
Essential
Questions

5. Warm Up
4 X 8
9 X 7
5 X 5
3 X 6
8 X 6
7 X 7

6. Today’s Lesson
In this lesson, you will learn an algorithm to help you record the partial products as you multiply.
Let’s look at the Envision Video for this lesson and take the quiz.

7. Think and Write
We use arrays to solve multiplication problems by representing the problem as a number of rows with equal objects in each row.
In real life what can you think of that comes in rows?
Picture albums, desks in a classroom, chairs in an auditorium, plane seats, etc.

8. Arrays
Array: A strategy used to solve a multiplication problem by drawing equal rows with an equal number of objects in each row. (Enter this definition in your Interactive Math Notebook)
Example: For the problem 2 x 4, you would make 2 rows with 4 objects in each row.

9. Partial Products with Arrays
How can you make an array to show 4 X 12?
Look at the tens and ones in the 12 as two different numbers. Make an array for 4 X 1, and another for 4 X 2.
Remember that since the 1 is in the tens place, and 4 X 1 = 4, it is really worth X 2 = 8
Now add

10. Problem 1
Matt arranges his video games in 4 rows with 16 games in each row. Build an array to show Matt’s games.

11. Problem 2
Abby bakes 3 rows of cupcakes with 14 cupcakes in a row. Build an array to find out how many cupcakes Abby baked.

12. Problem 3
Tyler puts his baseball cards in 4 rows with 26 cards per row. Build an array to find how many cards Tyler has in all.

13. Problem 4
Gavin puts his dinosaurs into 3 rows with 22 dinosaurs in each row. Build an array to see how Gavin arranged his dinosaurs and find his total number of dinosaurs.

14. Problem 5
Kara bakes cookies in 6 rows with 16 cookies per row. Build an array to find out how many cookies Kara baked in all.

15. Challenge
How many more stamps are in 4 rows of rocket stamps than 5 rows of flower stamps?
Type of Stamps
Number Per Row
Rocket 30
Presidents 24
Flower 22

16. Lesson Wrap Up
In this lesson, you recorded multiplication after finding partial products using an expanded algorithm.
Reflection in Notebook: At the end of this unit, I want to be able to... 
Center Activity – Toss and Talk (6-1).
Homework (6-1 Practice) for one “Paw Signature” and (6-1 Reaching & Practice) if you want two “Paw Signatures.”
Website for Practice: Website for Practice: