Why ‘5+5+5=15’ is wrong under Common Core?
Here’s a “repeated addition” Common Core problem that’s taught in third grade in US schools:
Use the repeated-addition strategy to solve 5×3.
If you answer the question with 5+5+5=15, you would be wrong.
The correct answer is 3+3+3+3+3.
Mathematically, both are correct. But under Common Core, you’re supposed to read 5×3 as “five groups of three.” So “three groups of five” is wrong.
According to Common Core defenders, this method will be useful when students do more advanced math. This way of reading things, for instance, can be used when students learn matrices in multivariable calculus in high school.
But parents aren’t happy about it.
The above information is taken from an article entitled Why 5+5+5=15 is Wrong Under Common Core. From it we can see that good old Common Sense is missing from Common Core.
One person in an article entitled Why Was 5 x 3 = 5 + 5 + 5 Marked Wrong? gives his justification for the teacher marking the student’s answer as wrong. Well his reasoning is gobbledygook (nonsense) as far as I am concerned. To tie learning to solve 5×3 in third grade to learning “matrices in multivariable calculus in high school” lacks Common Sense. Learning matrices has nothing or at least very little to do with knowing how to solve 5×3.
Note that this is a third grader. They say they are teaching the student something he/she will need in high school. What are they doing between third grade and high school?
This just proves my long standing observation that one major problem with our present day school system is that we are imposing more on children than they need. Let them be children for goodness sake according to their age.
God gave them the ability to think. Stop thinking you need some mechanical or human contrived system to teach them how to think six/seven years away.
Just get back to the basics: the old 4Rs: “reading, riting, rithmatic, and recess”. It wasn’t good English but it sure did work for my generation.
And by the way I became a Computer Programmer 4 years after High School and I had no computer training in Elementary or High School. I obtained a B.S. in Computer Science. I did it all because I did learn the 4Rs in elementary/high school. I had the foundation and I built upon it. That is all kids need and they will build upon it. Oh yeah, I had no problem programming matrices in my Computer Science training nor in the work environment.
Clearly that kid used his thinking ability in that problem. Like anybody else he started with the first number and added it three times. But even if the problem had been 3×5 starting with 5 is what a person who understands math would do. Who in their right mind would start with 3 and add it 5 times. The latter would not be very smart and takes more time.
He should have gotten extra points for thinking.
Now I am pretty sure he was taught at some point that both ways were right. Now if he was told to do it a certain way and not to do it the way he did it, then I could understand deducting points. That is, if it was an exercise in obedience rather than preparation for “matrices” some six/seven years away. But the reasoning the educator gives is a non-starter for me.