When groups are
not equal, you
add to find how many. 
2 + 1 = 3
multiply: cannot 
When groups are
equal, you
can add or multiply.

2 + 2 = 4 or
2 x 2 = 4 
Example: Not
Equal Groups
Serena bought
3 packages of batteries. Two packages had 2 batteries each.
The third package had 3 batteries. How many batteries did Serena
buy? 

Equal groups? no
Add: 2 + 2 + 3 = 7
Multiply:
cannot 


Example:
Equal Groups
Kevin
bought 3 packages of batteries. There were 2 batteries in
each package. How many batteries did he buy? 

Equal groups? yes
Add: 2 + 2 + 2 = 6
Multiply:
3 x 2 = 6
