Letting Life Lead
I am so sick of these common core memes and videos.
Watch it: Common Core Video
The person in the video is actually demonstrating a simple concept. Basic number sense. You can add up instead of subtracting to get the answer. What the woman is showing is just one way to demonstrate visually this very important concept (see my rant Part 2). Adding up is what we do in our head all the time.
When we subtract 1999 from 2000 in our heads, do we do 2000 – 1999 and borrow? No! We think: 1999 + 1 is 2000. Therefore, 2000 -1999 is 1.There are several other ways to find a subtraction answer other than borrowing. You use different skills that fit the situation. Borrowing works great with pencil and paper (and we should all know how to do it), but it is difficult to do in your head. The bigger the number, the more impossible it gets to do the calculation mentally.
We also do things like “add in and subtract off” when we deal with money. We like round numbers. Particularly numbers that end in five or zero when doing mental arithmetic.
We don’t do $20.00 – $5.89 by borrowing in our head. That’s crazy. Trust me, I know because I used to try to do that all the time! I couldn’t figure out how people were doing the borrowing so fast in their heads. It frustrated me to no end. News Flash: They weren’t borrowing!
We might decide to add in change or subtract it off so we can do the arithmetic easier then adjust it when we are done. Or, if we are at the register and someone gives us a $20.00 bill we ADD UP/COUNT UP.
$0.89 plus *11 cents* is $6.00
plus *four dollars* is $10,
plus *ten dollars* more is 20 dollars.
Total change $14.11.
No borrowing necessary.
And people will be impressed when you can still make change when the power is out. And if they give you $20.89 you can grin and give them $15 without breaking a sweat.
There is nothing wrong with common core skills. They have always been basic skills.
I have seen people complain about problems like this:
Add 206 + 104 without carrying.
If you understand that you can add numbers in any order, you have number sense and you can do this problem in your head without having to carry.
A child needs to understand place value. And they must understand that the value doesn’t change whether the number is in one group or many. We can see 206 as 200 plus 6. We can see 104 as 100 plus 4. If a child understands the concept of pairs of numbers that add up to ten. They can easily recognize that six ones plus four ones is 10. All they have left now is 200 plus 100 which is 300. The answer is 310. This may seem “longer” until you realize that knowing how to break the numbers up into manageable pieces is the key to mental math. We can also add 206 + 104 going left to right but still separating the hundreds from the ones. 200 + 100 is 300. Plus six more is 306. Plus four more is 310.
You fit the skill to the situation and your preference.
I am a huge supporter of homeschooling. However, if a concept like this is too difficult and confusing then I cannot recommend that a person teach math at home themselves (they may need to hire someone or find a supplement). Number sense is a crucial skill. It’s much more than memorizing the steps to borrowing, carrying, or long division. Lack of number sense makes learning certain concepts in higher mathematics very difficult. I didn’t even understand prime numbers until college. I had no idea how to use them and I didn’t know how to find them — I just memorized a dozen and hoped my guessing instincts would carry me through.
Common Core rules that force teachers to teach to useless tests and put undue pressure on students to perform is another issue entirely. That is what’s wrong with common core. Regulation not the basic skills. Focus attention on the shackles on teachers and the stupid tests. Complain about the ridiculous amounts of homework given to students and the lack of enough recess.
I teach some of these basic skills to my adult students. They are usually relieved that they have another way to work with large numbers or can finally do simple mental math without having to try and visualize borrowing. Sometimes the concept is very simple such as saying, “You know, you can add up your columns of numbers left to right, rather than going backwards and carrying right to left.” Minds blown.
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