Part part whole is our math graphic organizer. We use this to determine if a word problem is addition or subtraction. I ask "Do we know the parts or the whole?" If we know the parts we are adding. If we know the whole and one part we are subtracting. This helps the students realize that they can't use the key terms (the words more or less) and assume that they know the operation being used.
Lindsay had 6 black dogs and 2 brown dogs. How many dogs did she have together?
This tells us we are missing the whole. Now we know we add. ___+___=___
Lindsay had 8 dogs. 2 dogs are brown and the rest are black. How many black dogs are there?
This tells us we are missing a part. Now we know we subtract. ___-___=___