1. Multiplying with 3
MAFS.3.OA.3.7

2. Lesson Opening
Solve the two problems below. Write the equation you used to solve the problem.
Jason ate 2 bags of candies. Each bag contained 9 candies. How many candies did Jason eat?
Liza has 10 photos that she wants to put onto 2 pages in a photo album. If she put the same number of photos on each page, how many photos will be on each page?

3. Lesson Opening
Solve the two problems below. Write the equation you used to solve the problem.
Jason ate 2 bags of candies. Each bag contained 9 candies. How many candies did Jason eat?
Liza has 10 photos that she wants to put onto 2 pages in a photo album. If she put the same number of photos on each page, how many photos will be on each page?
2 bags (groups) of 9 candies
2 x 9 = 18
Jason ate 18 candies.
10 photos on 2 pages (groups)
10 ÷ 2 = OR 2 x ___ = 10
There are 5 photos on each page.

4. Multiplying with 3 Multiplying by 3 is the same as tripling a number.
You can think of this as doubling a number, then adding another set.

5. Multiplying with 3
Multiplying by 3 is the same as tripling a number.
You can think of this as doubling a number, then adding another set.
If I have a set of 4 utensils, how many utensils would I have if I had 3 sets?

6. First, double the number in a set.
Multiplying with 3
Multiplying by 3 is the same as tripling a number.
You can think of this as doubling a number, then adding another set.
If I have a set of 4 utensils, how many utensils would I have if I had 3 sets?
First, double the number in a set.
4 × 2 = 8

7. Multiplying with 3
Multiplying by 3 is the same as tripling a number.
You can think of this as doubling a number, then adding another set.
If I have a set of 4 utensils, how many utensils would I have if I had 3 sets? +
First, double the number in a set.
4 × 2 = 8
Then add the number in another set.
8 + 4 = 12

8. So, 3 groups of 4 or 3 × 4 is 12. 3 × 4 = 12 + Multiplying with 3
Multiplying by 3 is the same as tripling a number.
You can think of this as doubling a number, then adding another set.
If I have a set of 4 utensils, how many utensils would I have if I had 3 sets? +
First, double the number in a set.
4 × 2 = 8
Then add the number in another set.
8 + 4 = 12

9. Multiplying with 3 Multiplying by 3 is the same as tripling a number.
You can think of this as doubling a number, then adding another set.
You can also skip count by 3s.

10. If I have 4 sets of 3 strainers, how many strainers do I have?
Multiplying with 3
Multiplying by 3 is the same as tripling a number.
You can think of this as doubling a number, then adding another set.
You can also skip count by 3s.
If I have 4 sets of 3 strainers, how many strainers do I have?

11. If I have 4 sets of 3 strainers, how many strainers do I have?
Multiplying with 3
Multiplying by 3 is the same as tripling a number.
You can think of this as doubling a number, then adding another set.
You can also skip count by 3s.
If I have 4 sets of 3 strainers, how many strainers do I have? 3, 6, 9, 12

12. If I have 4 sets of 3 strainers, how many strainers do I have?
Multiplying with 3
So, 4 groups of 3
or 4 × 3
is 12.
4 × 3 = 12
Multiplying by 3 is the same as tripling a number.
You can think of this as doubling a number, then adding another set.
You can also skip count by 3s.
If I have 4 sets of 3 strainers, how many strainers do I have? 3, 6, 9, 12

13. Multiplying with 3 Let’s practice doubling, then adding another set
3 groups of 5: ______________________________
3 groups of 2: ______________________________
3 groups of 6: ______________________________
5 × 2 = 10
5 + 5 = 10
First, double 5
Then add another 5
= 15
So, 3 groups of 5, or 3 × 5 = 15
2 × 2 = 4
2 + 2 = 4
First, double 2
Then add another 2
4 + 2 = 6
So, 3 groups of 2, or 3 × 2 = 6
6 × 2 = 12
6 + 6 = 12
First, double 6
Then add another 6
= 18
Some students get confused about which number to double and then which number to add. Remind them that if they are using a “3s strategy” they are going to “do” the strategy to the OTHER factor.
So, 3 groups of 6, or 3 × 6 = 18

14. Multiplying with 3
Let’s look at our Multiplication Table…

15. Multiplying with 3
Find all the multiples of 3…

16. Multiplying with 3 Find all the multiples of 3…
The multiples have a pattern of even, odd, even, odd…
Find all the multiples of 3…

17. Multiplying with 3
Let’s look at our 100 Chart…

18. Multiplying with 3
Find all the multiples of 3.

19. Multiplying with 3 Find all the multiples of 3.
The multiples have a pattern of even, odd, even, odd…
A diagonal pattern is made.
Most of the rows have 3 highlighted multiples.
There are usually only 3 multiples in each new tens place.
There are 2 spaces between each highlighted place in the rows and columns.
Find all the multiples of 3.

20. Game: All Lined Up What you need: Game board
Spinner, 10-sided die, OR digit cards
How to play:
The shorter player starts.
Spin, roll, or draw a digit card and multiply that number by 3.
Place your product in one of the six empty boxes on your game board.
The numbers must be placed in the correct number sequence. (If a player has a 3, 9, and 15 in the first three boxes, and spins a 4 to get a product of 12 on her next turn, she cannot play the 12 and loses her turn.)
The first player to fill all six boxes wins.

21. What is one strategy you used for multiplying with 3?
Closing
What is one strategy you used for multiplying with 3?
Skip count by 3
Double the other factor, then add the other factor
Draw it/model it

22. Exit Ticket
Hoover has 7 shelves with 3 hats on each shelf. How many hats does Hoover have?
Model the problem.
Write an equation that corresponds to it.
Write another equation that corresponds to it.
Write the answer to the problem in a complete sentence.