1. Multiply and Divide within 100
3.OA.7
Multiply and Divide within 100

2. Multiply by zero
What will the answer be…..
8 X 0 =

3. What will the product be?
9 x 0 =
0 x 3 =
7 x 0 =
1,999 x 0 =
0 x 99,999 =
Assign numbers to 5 students and have the students ready to answer the problem. Have the students prove or tell how they know the answer.
9 x 0 = 0 because you are taking 9 groups zero times.
0 x 3 = 0 because you are taking 0 3 times which still leaves you with zero
On number 4 and 5 see if students can say the number names correctly - # 5 is above 3rd grade level but you might have a student who can do it.

4. What will the product be?
9 x 1 =
1 x 3 =
7 x 1 =
1,999 x 1 =
1 x 99,999 =
Assign numbers to 5 students and have the students ready to answer the problem. Have the students prove or tell how they know the answer.
9 x 1 = 9 because you are taking the number 9 1 time
1 x 3 = 3 because you are taking 3, 1 time
etc.

5. Doubles multiplying by 2
2 x 4 can be thought of as 4 doubled
2 x 6 = ?
Explain how you know the answer based on doubles

6. Doubling twice multiplying by 4
4 x 5 can be thought of as 5 doubled twice
Can someone explain this?
Does this work anytime you multiply a number by 4?
5 doubled once is 10 double it again you get 20
Let students explore doubling twice with 4 x a one-digit number
This is a strategy they could use when multiplying by 4

7. Doubling three times multiplying by 8
8 x 5 can be thought of as 5 doubled three times
Can someone explain this?
Does this work anytime you multiply a number by 8?
5 doubled once is 10 double it again you get 20 double the 20 and you get 40
Let students explore doubling three times with 8 x a one-digit number
This is a strategy they could use when multiplying by 8

8. Tens
If we know 6 tens is 60. how can this help us with multiplying by a 10?

9. Square Numbers Why would we say 9 is a square number?
Use 1 inch tiles or draw a picture to make another square number.

10. Multiplying Nines
When you multiply by 9 you can think of as 10 groups minus one group of 3.
Explain how you can relate:
3 x 10 = 30
3 x 9 = 27
Try to solve this problem mentally
9 x 6
When they do 9 x 6 we want the students to think
10 x 6 is 60
60 minus one group of 6 = 54

11. Decomposing I don’t know what 6 x 7 is
I do know 6 x 6 = 36 so I just need one more group of = 42
I will decompose the 8 into 5 and 3
x 4
5 x 4 = 20
3 x 4 = 12
What does 8 x 4 = ?

12. What multiplication problem is represented here?
6 x 5 or 5 x 6 are both acceptable

13. How can you solve this multiplication problem by splitting it up into two easier known products?

14. Ready, GO!!
4 x 7
8 x 3
6 x 9
5 x 4
Let students solve these multiplication problems mentally or on a white board. Click through and give students a little bit of time to solve each one. They may need to draw a picture or an array. Hopefully they are using some of the strategies practiced. This standard is really looking for students to use the decomposing or distributive property strategy.
Ask for answers and strategies once they have solved all 4