Because that is what is being taught. It doesn’t matter if there is some better theoretical way of teaching it. That is the way they are actually teaching it.
Is this complaint specific to this particular teacher who is blaming common core for this travesty? Why are some of the posters defending this idiocy as common core if this is not representative of common core?
No link to Tom Lehrer: New Math yet? Yous people is getting slow!
CMC fnord!
Does it have the Common Core stamp in the corner of it?
IIUC correctly, “Common Core” is a What, not a How. Common Core defines what children are learning, not the way it’s being taught.
Previous thread in GQ: What Common Core math technique was that check mocking?
In that thread, even sven said
But other posters are disputing this, including Joey P, who seems to have the same complaint you have.
The last time I looked into this, I found cites for mathematicians defining it both ways.
So if a teacher is marking one way or another wrong they’re enforcing an arbitrary and non-universal convention. And they’re just going to have teach the commutative property soon anyway…
That seems to be how it is being applied in the real world.
What you seem to be saying is that this is just a bad teacher who doesn’t understand common core, right? Well, let me suggest that there is a reasonably large population of 3rd grade teachers who are too fucking dumb to implement common core the way that education policymakers think it ought to be implemented.
Once you understand multiplication as a concept it is largely a waste of time to NOT use the algorithms.
Algebraic concepts have been a part of 3rd grade math for at least half a century. Division is mostly accomplished through algebraic concepts, it also requires you to have almost memorized the multiplication tables to do quickly and effectively.
KNOWING that 78=56 and 79=63 makes it a lot easier to know that 60/7=8 plus some remainder. You don’t have to sit there and do 60-7=53-7=46-7=39-7=32-7=25-7=18-7=11-7=4, then count up all the 7s you subtracted to get the number 8. You stop doing division that way after the first week or so.
What the common core people call memorization can also be referred to as knowledge.
This is the way it is being taught. My kid’s teacher is not unique.
7 times 3 mean 21 to me. What does it mean to you? IN what way does it matter if you get 7 groups of 3 or 7 repeated 3 times?
The thing about math is that it is frequently true that if you apply ANY concept incorrectly, you get the wrong answer.
If common core upsets the OP this much, I can only imagine how he’ll react to aristocratic core.
Did you read what I posted? That is Common Core. A list of objectives that lesson plans need to accomplish. If your district is misunderstanding them, or your child’s teacher misunderstands the district mandates, that is not on Common Core.
Look at the two sections of third grade requirements that I highlighted. If the are working on the red section and it is a word problem about something that only comes in groups of 3, and they did but adding 7 three times, they missed the point of the exercise. If it is just a written problem of 3x7, then it is poorly written.
One of the issues/features of Common Core is that the implementation is entirely up to the the states.
You have the context.
My kid was asked to answer math questions and to show his work. One of them was:
7*3=
If you were to try to find the answer to this, you might think that the easiest way to get this answer while showing all your work would be to add 3 numbers together. Nope that would be wrong. You have to add 7 numbers together.
Damuri Ajashi, lots of people have asked how you know this is Common Core, without explaining why they’re asking. Modern math teaching is trying to actually teach kids the math concepts and not just memorize tables. There’s good reason for doing this, even though I find it amusing when I give a clerk $20.12 when the tab is $9.87, and watching the bewildered look on their face after they’ve entered into the register that I simply gave them $20.00 even.
When I learned math back in the 60s, there was starting to be some of that Tom Lehrer “new math” where we learned about sets and different number bases, but lots of the basics were still memorizing multiplication tables for the single-digit numbers and rote learning of a mechanism to adapt those to numbers with more digits. Those work for getting the right answer, but don’t do much for acquiring a numbers sense. And is the old way really important? If I want to multiply a couple of multi-digit numbers, there’s never a calculator more than two feet away from me.
So modern math teaching is trying to give kids a sense of how numbers work, not just having them memorize an opaque and nearly obsolete process that can yield the correct answer.
And finally, this has been going on for quite a few years, while “Common Core” is just standardizing the best practices across the states.
He got partail credit for getting the right answer but lost points for getting it the wrong way. I don’t care about the actual grade, its third grade. I care about the confusing and incorrect message its sending to my kid that there is some significance to the order in which two numbers are multiplied.
You’re kidding right? There is a common core stamp? How does that prevent the teacher from applying stupid standards to the answers. I think she got the homework straight out of a teacher’s edition book and she was following the answer key.
The principles of Common Core may make sense but there certainly seem to be implementation issues. And this is a decade later. I will have to check again but I think the “answer key” to 7*3 is:
7*3=3+3+3+3+3+3+3=21
Perhaps we need to teach the teachers a bit better. Because they seem to be turning Common Core into a very rote form of math where 7*3=7+7+7=21 is wrong.
What you have there is a bad teacher. And she was a bad teacher even before Common Core, and was probably teaching in exactly the same way. The fact that she’s a bad teacher has nothing to do with the fact that 42 states got together and agreed that it’d make sense for all of them to teach the same things at the same grade levels.
I’ve watched a few YouTube videos on how math is being taught these days. Though I had no freaking clue what all the squiggles and dots meant when they were just put in front of me, after some explanation I think it’s pretty clear that these are novel ways to explain math in ways I rather wish I had some exposure to when I was in school.
The comparison to martial arts is apt. Martial arts is not simply about repetition and rote memorization of various techniques. If you want to execute some kind of takedown, it’s reasonable to expect a decent student to show not only that they can execute the technique if the attacker starts in ready position; steps forward with a single punch; and basically pauses until the defender can execute the technique they have memorized. They should understand both how to adapt the technique to unplanned situations, and grok why the technique works to begin with.
Learning how imbalances among several axes on someone’s body will make them fall down – that is, the basic principle of a takedown – adds context to the action and allows a person to tinker with their technique and experiment with the principles in order to become better.
So, in the same manner – teaching kids some of the principles behind math in order for them to know how to solve the problem in various ways seems like a good idea; demanding that the multiplication tables AND NOTHING ELSE DAMMIT be pounded into their head seems like a poor idea.
If you are working in pure math sure. In the real world sometimes it matters. Take eggs.
Eggs come in cartons of 12. If you are just counting cartons and figuring out how many eggs you have then you can do X12 or 12X and get the right answer. But if have a more complex question it matters if they understand how the concept is being applied.
Common core shifts some of the emphasis from memorizing math facts (they are still taught, just not as emphasized) to math sense. Understanding how numbers work and why. There are a lot of math algorithms that are either no longer taught or emphasized. My algebra teacher showed us the algorithm for finding square roots once, just so we could see it. I have never used or or seen it since. Is that problem?
My 6th grade just brought home a worksheet on factoring. When I did it, I would have had to shown how I divided each large number by the possible factors to determine if there was a remainder. His wanted him to explain how he eliminated each one: Didn’t end in 0 or 5, added digits and weren’t divisible by 3, etc. Those were “tricks” I learned in SAT prep. He even had ones that I never saw before. His way was much faster and, if done properly, will give him a better basis for understanding how bases work later on.
I wondered whether they had been given specific instructions on how to carry out the multiplication.
It could just be that the answer key shows a way to do it, and the teacher is wrongly interpreting it as the only way to do it. In which case, yeah, we need smarter or better-trained teachers.
Or it may be that the children are being explicitly taught that X*Y means X Y’s added together, and not Y X’s added together, though by the magic of the commutative property these turn out to have the same value. In which case, okay, but I’m not sure there’s a standard, generally-understood meaning of what the order in multiplication is supposed to signify.
Keep in mind that this is an approach used when first learning multiplication. For those newly exposed to the concept of multiplication, the associative, commutative, and distributive properties of multiplication are a foreign concept.
It is perfectly natural, then, to present the expression “3 x 7” as “three groups of seven” and “7 x 3” as “seven groups of three”. Remember, these kids don’t know that multiplication commutates, so they don’t intuitively know that “3 x 7” is equivalent to saying “7 x 3”. This concept is yet to come.
“Seven groups of three” and “three groups of seven” may have the same total, but they are not the same.