I stumbled across another misinformed, incorrect video purporting to show how “frightening” the common core standards are.
The mathematical issues brought up in this video are the same as the issues I address in many of the other posts about Misunderstanding the Common Core. Please read those. But, here are some new thoughts that this video created in me.
Thought #1 – The anti-common core movement really likes to pick on the idea of subtraction! I wonder why? There must be hundreds of other standards and yet, apparently, only subtraction brings up these emotionally charged challenges to the common core standards. Are we to think that if subtraction is “frightening” then all other standards are “frightening as well?” Is that good thinking?
However, as I have tried to explain in the other posts, the method of subtraction shown in this video is not bad! The lady in the video shows how 43 – 13 is computed. First, 3 – 3 is zero…write a zero below the 3’s. Then, 4 – 1 is 3…write a 3 below the 4 and 1. The answer is 30. Done.
The so-called common core method to subtract is a method related to counting back change. It is a method where one counts back, starting at 13, to 43. Thirteen plus 2 is fifteen. Fifteen plus 5 is 20. Twenty plus 10 is 30. Thirty plus 10 is 40. Forty plus 3 is 43. Note, we counted back 30 units. Therefore, 43 – 13 = 30. No big deal.
Thought #2 – Even though I have no problem with the “counting back change” method as ONE POSSIBLE method to subtract 43 -13 = 30, this is not the “common core way” as reported in this video. I challenge any reader to show where, in the actual common core standards document, it says that subtraction must be done in this way or any particular way! In fact, I find the following standard:
To say that the common core standards require one method of subtraction over another is just not true.
Thought #3 – Just because a person doesn’t understand something does not mean this is a bad thing! I think that the lack of mathematical content knowledge of the general population in the US is a big reason for the so called “frightening” aspects of the standards. As I have tried to explain in all of these posts, there is nothing frightening about the standards! Rather than to react to something that one doesn’t know much about, I challenge everyone to become more aware of the standards. Read them. Ask questions. Study. Then if you have a legitimate, well-reasoned concern, then certainly engage in a respectful discussion about the issue!
This sounds like something we could all learn to do in other areas of our lives as well…
Scott
getrealmath 