3-12 Subtracting a Group

3-12 Subtracting a Group

Fill in the Blank

 $2\times5=?$  

Fill in the Blank

 $2\times6=?$  

Fill in the Blank

 $2\times7=?$  

Fill in the Blank

 $10\times3=?$  

Fill in the Blank

 $10\times4=?$  

Fill in the Blank

 $10\times5=?$  

Fill in the Blank

 $4\times5=?$  

Fill in the Blank

 $5\times5=?$  

Fill in the Blank

 $6\times5=?$  

Math Message

• Make an array on your whiteboard for the following question: There are 5 rows of 4 chairs for a class show. Write a number model for the total number of chairs.

• Change your sketch to fit this situation: 4 people are not coming, so you need 4 fewer chairs. Write a number model that shows the new total number of chairs.

Fill in the Blank

How many chairs are in your new array?

Solve

Danielle has 10 toy tricycles that each have 3 wheels. How many wheels are there all together?

Fill in the Blank

What is the number model to go with Danielle's story?

Danielle lost 1 tricycle.

How many total wheels are there now?

Fill in the Blank

How many total wheels are there after Danielle loses a tricycle?

Solve #1 on Math Journal Page 93

Multiple Choice

What helper fact does your first sketch show on #1?

• $4\times9=36$

• $4\times10=40$

Solve #2 on Math Journal Page 94

Open Ended

If you wanted to solve

 $4\times8$   using the subtracting-a-group strategy