A short video on how addition and subtraction facts are “related”.
I have been playing with a new drawing tablet. I’m getting the hang of it although my drawings are very primitive! This is a video on one way to explain fact families to a child. My students get confused when they have to do the inverse operation so this helps them visualize it and relate it to something tangible.
The idea is that children understand that families come in all sizes and shapes. They can be mom, dad, baby sister and Joey. Or Grandma, Billy and Susie. They all make up a family.
Now let’s put a number with a person. Say :
- Dad is 11, Ted is 3 and Bobby is 8.
It doesn’t matter is we say it in that order or:
- Ted is 3, Bobby is 8 and Dad is 11.
If we add the plus sign (+) for addition it would look like this:
- 3 + 8 = 11
Would it matter if we say,:
- 8 + 3 = 11
Has it changed the meaning or the answer?
How about if we said Dad first?
- 11 __8 = 3
Would we still say +? Does it make sense? What is the opposite of addition? If you students aren’t sure, draw a picture to show you start with 11 but end up with 3. What happened? Once they determine they have to subtract, you can go to the next step.
- 11 – 8 = 3
- 11- 3 = 8
Let you students play around with this concept in a number of ways to insure that they truly understand the concept.
Let me know what you think!