What is 32 minus 12? I bet you did your math wrong, according to "Common Core"...
16 2014-09-29 by strokethekitty
Instead of just subtracting 12 from 32, they are teaching first graders to do it this way.
Add 3 to twelve to get 15.
Add 5 to fifteen to get 20.
Add 10 to get 30.
Now, add 2 to get 32.
Finally, add 3, 5, 10, and 12 to get 20.
The answer is 20.
Instead of:
Subtract the "Ones" place integers (2-2=0)
Subtract the "Tens" place integers (3-1=2)
Now, in the Tens place, there is a 2, and in the Ones place is a 0. This equals 20. (This isnt really a step.)
So, according to common core, it is better to teach simple arithmetic using FIVE steps instead of TWO.
Fuck common core...
80 comments
14 Ambiguously_Ironic 2014-09-29
That has gotta be the dumbest fucking arithmetic technique I've ever seen.
7 ct_warlock 2014-09-29
How many have you seen?
I mean realistically, people who don't like Common Core aren't going to pick an example that makes it look good are they?
-1 Ambiguously_Ironic 2014-09-29
What point are you attempting to make? Do you disagree that the arithmetic technique in the OP is completely idiotic, confusing, complicated, and convoluted when compared to the way we were all taught subtraction growing up?
4 [deleted] 2014-09-29
No actually its very intuitive if you've been brought up with it.
0 Ambiguously_Ironic 2014-09-29
Common Core is only a few years old - no one has "been brought up with it" yet.
-2 Samurai_light 2014-09-29
I was in gifted and accelerated classes and this is how we were taught.
9 djbattleshits 2014-09-29
For a problem like this, this makes zero sense.
here's a better problem -
initially, you're like.. uh.. too many numbers, and then you get out pen and paper.
to do this in your head, you break it down into smaller chunks -
500-300 = 200
40-40= 0
5-2 = 3
Answer =203
I still can't get the subtraction method described.It would be easier to understand if it were
3-1= 2
2-2 = 0
Done. 20 but no, because un-common core.
3 BroJaKsc2 2014-09-29
Actually the common is just doing what you're doing but simplifying the steps.
545 - 342 = ?
342 + 3 = 345
345 + 200 = 545
203
1 djbattleshits 2014-09-29
right, but why would you add when you could subtract? why would you teach students that they have to add to subtract it's so backwards...
3 [deleted] 2014-09-29
Because its to help kids that don't know how to subtract yet
-1 djbattleshits 2014-09-29
......... what? Let me teach you how to subtract by adding? That still makes no sense. Give the kid 36 cookies, tell him to eat 25, and besides diabetes he then has 11 cookies. boom subtraction taught.
Adding seemingly random numbers to other numbers to total up how much you subtracted is just a mindfuck.
5 [deleted] 2014-09-29
No. You only think that's easy because youve been taught that way. But to kids adding is easier than subtracting and to understand how these numbers can be manipulated to make subtracting easier is a concept well worth learning.
-1 djbattleshits 2014-09-29
The obvious goal is to take parents entirely out of the equation then, because if the parents can't help their kids, and teachers are overworked, in overcrowded classrooms and forced to teach to tests as defined by elected officials funded by various (and sometimes unscrupulous or nefarious) means, the students are the ones getting left behind.
I'm only 8 years removed from High School and this is a concept I have not been taught. You can't expect any parent in Generations X or Y, or older to be able to assist their children in the learning process, and schools are not equipped to deal with any extra tutoring that would be needed to change a standard of learning that has been in place for decades. The US is so far behind the rest of the developed world in math scores, putting students on an island, having to learn entirely alone, being taught by teachers who weren't until recently trained on this standard, being marooned by parents who have no idea what the hell any of this means, and having to figure it all out themselves.
I don't see how that benefits anyone, given the sheer lack of support network for students/children.
3 [deleted] 2014-09-29
I understand it. Just takes some looking into
1 iamy2k 2014-09-29
545 - 300 = 445, 345, {245}
245 - 42 = (45-42= 3)
203
7 Nubby82 2014-09-29
Where are they getting the 3-5-10-2??? I did mental math and it was, "well shit, 2 minus 2 is zero, and 3 minus 1 is 2. So its 20. But, where are they getting these other numbers to add? This shit doesn't make any damn sense."
5 strokethekitty 2014-09-29
If you add 3 to 12 you get 15, which is a multiple of 5 and therefor easier to apply math.
Then you add 5 to get 20 which is a multiple of 10, and even easier to apply math.
Then you add 10 to get 30, which is close to the 32 we are originally trying to deduct 20 from.
Then, all thats left is the 2 to get to 32.
When you add up all of these additions to 12, you get 20, and this, 32-12=20.
5 Nubby82 2014-09-29
Such a convoluted way. And such a round about way. I feel sorry for kids that have to learn this way.
-1 LizardKingRumsfeld 2014-09-29
I think the idea is that kids aren't learning this way.
-2 Samurai_light 2014-09-29
Yes, it's harder than typing numbers into a calculator (like the "old fashioned" way), but it teaches them to actually use critical thinking and relate numbers to each other. And when they start using larger numbers and algebra, this is much more useful than just punching numbers into a formula and spitting out an answer with little actual thought or understanding.
1 vapeh0le 2014-09-29
Why in the world would we be trying to teach kids to do all this instead of simple arithmetic?
It's like, if you're trying to put oil in your car, but instead of just popping the hood, removing the oil cap and pouring the oil in, they want you to take the radiator out and disconnect the battery first. But why? How is it simpler?
Are they trying to rewire the way kids approach math? Why? Are kids not having enough difficulty with it already?
1 Samurai_light 2014-09-29
Do you want to teach kids to just type the numbers in a calculator, or understand numbers and use critical thinking? Putting the numbers into the "old fashioned" way formula doesn't teach kids much more than just typing it into the calculator. Do 1436-749 in your head.
800->1000 = 200
1000->1400 = 400
400->36 = 36
50->100 (750-800) = 50
9->10 (749->750) = 1
200+400+36+50+1 or 600(200+400) + 80(50+30) + 7(6+1) = 687
0 LizardKingRumsfeld 2014-09-29
It's newspeak but for math.
3 Samurai_light 2014-09-29
Let me give you a better example. Do 936-588 in your head. Can you?
900->36 = 36
600->900 = 300
90->100 = 10
8->10 = 2
So, 2+10+300+36. Or 300+40 (30+10)+8(6+2). 348
EDIT: I actually messed up my own example, lol! Fixed it now.
Or think of it in terms of counting back change when the register breaks. Total is $13.46 and they hand you a $50. Are you going to keep a pencil and paper and hand write every equation out in the old formula or break it down into chunks you can manage in your head?
$14->$20 = $6
$20->$50 = $30
.50->$1 = .50
.46->.50 = .04
$30 + $6 + .50 + .04 or $36.54
4 Dreamofreason 2014-09-29
In terms of making change, I don't think either example is good. If total is 13.46 and they gave me $50, I would count out 4 pennies to get to .50, then add .50 to get to the next dollar, which is 14. Add $1 to get to $15, then a $5 to get to $20. Add a$10 and a $20 to get to $50....so:
46+4= 50 50+50= 100 14+1= 15 15+5=20 20+10= 30 30+20=50
Writing it out, it seems kinda crazy but in my years of working retail where the register didn't tell you the amt to give back, this was the method I used.
1 Samurai_light 2014-09-29
Which is essentially what they are teaching. To break it down into chunks that are easier to work with, rather than plugging the numbers into an algorithm with pen and paper.
2 xBladeDragonx 2014-09-29
Hmmm I don't know which math I just did in my head... For that money example:
I did
50 - 10 = 40
40 - 3 = 37
then 46 + x = 100
and somehow my head knew to take out 1 from 37 to get 36.54
I mental math weird...
Edit: Actually i did one more step...
1 Samurai_light 2014-09-29
At least it worked and you were comfortable enough with numbers for your brain to critically break it down, rather than relying on the formula on paper to do the work for you.
-1 trikster2 2014-09-29
Wow this is hilarious because you got your own example wrong!
Your third step should be going down to 90 not 80. The answer is 348 not 358.
I'll stick with just doing math the old fashioned way: https://duckduckgo.com/?q=936-588
2 Samurai_light 2014-09-29
I knew if I typed enough of these, I would mess up. Doesn't really prove anything though. Is there a flaw in the logic? In the system? Could you do that math in your head? Other than my personal error, can you really provide any actual criticism, other than "It's different. I don't like it."?
1 Jesus_Harold_Christ 2014-09-29
I'm a bit miffed that your answer was upvoted and /u/trikster2 answer was at -1.
No, but logically correct does not infer that it is the best solution.
Yes, it's overly complex. It's susceptible to human error, because it is complex and has numerous extra steps.
Of course. Even at age 6, but I've always been "good at math". Also, I wouldn't use your algorithm in my head, because it's too complex and results in too many steps.
The problem I see is, how many numbers can you remember in your head? Maybe 3, 4, 5?
Does your system allow you to do it in your head? You couldn't even get it right after writing it down.
The only number I need to memorize is '12', and I can do it in my head.
588 + 12 = 600. Stick that 12 in your head.
936 - 600 = 336.
Now, add the 12 back and you get 348.
But, here's the real kicker. Do it however the fuck you want! Don't force me to carry the 1, don't force me to use your stupid algorithm. I do what the fuck I want. If I get it right, and I can do it faster than you can type the question into a calculator, what's the problem?
4 ThingsIveSeenandDone 2014-09-29
That problem isn't common core, it is one implementation of common core.
Common core is just a standard of what kids should know, not how could should be taught to know these things.
3 Fleshpeeler 2014-09-29
I understand it's probably not perfect but I think it's good to teach kids other ways of solving problems in many different subjects. I also don't see why this is posted here. It's not a conspiracy it's a work in progress. Most states will create their own form of common core that will probably fix quite a few of the issues rising up. http://www.corestandards.org/about-the-standards/myths-vs-facts/
3 strokethekitty 2014-09-29
According to some conspiracy theorists, common core is meant to confuse our children in an attempt to "dumb down america." Therein lies the conspiracy (theory).
-3 Fleshpeeler 2014-09-29
Oh ok. Didn't know people read that much into it. I don't think it's a conspiracy just a big change. Of course alot of people don't like change.
5 strokethekitty 2014-09-29
Fair enough. Im not exactly sure whether or not it is a conspiracy, honestly. I know many people do think so. All i know is thst i dont like common core.
I have tutored many kids in math, from algebra to college level calculus.
I found out that each student was doing bad at first not because they were stupid or couldnt understand the math, it was because their teacher couldnt teach. I asked them each to take notes in class, specificslly what the teacher was explaining, and to bring me their handouts they got from the teachers.
In every case, i found that the teacher was teaching horribly. I had to start, in many cases, a level or two in mathematics below what they were currently learning to teach the the fundamentals that are being applied in the course they were taking.
Once i taught (or, re-taught) them those fundamentals, and guided them and helped them to learn and understand what they were currently supposed to be learning, they got straight "A's".
The problem isnt the curriculum, which is what common core is changing. The problem is with the teaching, imo.
Hell, one of my students used a calculator to figure out what 10 divided by 0 was. I shit you not. I was like, dude, wtf? He told me his teacher lets them use the calculator for everything.
He was in calculus. I then took his calculator away and made him do all the math by hand from then on.
1 Dreamofreason 2014-09-29
How can you expect the teachers to be good at teaching it when none of them grew up this way and likely only had one workshop to "teach" them to do math and teach math in a totally new way.
I'm a high school teacher and hate common core. I teach art but it's having a negative effect everywhere. It's not the teachers fault. They are grossly underprepared to teach this stuff.
0 Fleshpeeler 2014-09-29
I completely agree.
-7 That_Republican 2014-09-29
So by dumbing down America, we'll have more Democrats. Then they can stay in power. I understand now.
9 strokethekitty 2014-09-29
Personally, i try my best to avoid the republican/democrat paradigm.
2 DwarvenPirate 2014-09-29
Study it out, brother, study it out!
2 DwarvenPirate 2014-09-29
And what is the point of that? Why isn't the way they do it now their 'common core'? Does Mississippi need to make a stupider way of doing it than Massachusetts or something?
2 Fleshpeeler 2014-09-29
Maybe? I've just heard some states are making their own form of common core. I live in Alabama and the big bitching here is that it's too hard. I'm sure my state will make it dumbed down for the trailer dwelling half wits that live here.
0 DwarvenPirate 2014-09-29
More likely dumbing it down so their teachers can more easily make their targets test scores.
3 TheRehabKid 2014-09-29
Just wanted to let everyone know that that arithmetic has nothing to do with the common core.
The common core is simply a "schedule" that tells us what kids should know by the time they finish a grade.
How the teachers get the kids there is up to them.
Go and actually research the common core.
3 DickTrachaeotomy 2014-09-29
It does make sense.
That is how I do it in my head.
There is a difference between 256 and 312 which comes from 25 to 30, and 6 to 12. 5 and 6. 56.
They're making it streamlined, if one can get it. It's a way to cut to the chase, using whole or half numbers (10 and 5 and smaller integers).
Now, parents might not get it but if you're a child learning a new language they might latch on. And parents can't help because they learned a different way and get frustrated when they can't use what they know.
Maybe if the PTO set up a common core math tutorial for adults, they'd be able to comprehend, allowing them to help their kids with the homework, instead of complaining about not getting it.
Dick Trachaeotomy for State House Rep 2050!
1 iamy2k 2014-09-29
This problem is fucked though. 12 and 32 both have a 2 in the tens place. So you can count up by 10's twice. Adding 5's two times was un-necessary.
2 princeyuuri 2014-09-29
Late to the party, but oh well.
This is literally the same way you count change. Say you're a cashier and someone gives you $20.00 to pay for a $17.46 transaction. You count it as such:
$17.46 + .04 = $17.50 (4 pennies)
$17.50 + .50 = $18.00 (two quarters, five dimes, or fifty pennies, so long as it adds up)
$18.00 + $2.00 = $20.00 (two one dollar bills, or a two dollar bill)
Now you're up to the original amount and you know the change is $2.54.
1 strokethekitty 2014-09-29
I guess some folks do it this way when counting change. I, however, have always figured out how much change was needed first, dished out the bills, then quarters, etc.
For instance, $2.54 change is two dollar bills, two quarters, and then four pennies. It was always faster for me to do it this way.
2 princeyuuri 2014-09-29
You could do it dollar first, too. Either way, the typical old school way of finding out change was counting from the bottom up, not figure the change first and then count it out. I've only ever seen older cashiers do it since the registers figure the change for you now, and I probably wouldn't have noticed it if my grandmother, who used to cashier back in her high school days, hadn't told me about it.
2 adviceguu80 2014-09-29
Waste of time. Just use a calculator.
2 archonemis 2014-09-29
I went to school and then dropped out because it was boring and a waste of time.
If I had to deal with Common Core I doubt I'd even have bothered myself to sit through middle school.
What a load of shit.
2 glugglug 2014-09-29
While this may be the silly new methodology being taught, it is NOT specified by the national common core standards. (It may be specified by certain states, I'm not sure on that.)
2 ct_warlock 2014-09-29
From what I hear this method is taught because it makes calculations involving much larger numbers easier.
Also I doubt the method we used prior to this just happened to the way people calculated numbers hundreds of years previously, and they managed okay.
2 Irradiance 2014-09-29
I remember showing my grandparents my adding skills, the method taught to me simply to write the numbers on top of each other then add the columns from right to left.
They said that they had learnt it from left to right, which on reflection makes it easier to do in your head.
1 iamy2k 2014-09-29
How would that work for 15 + 15?
15 + 15 = 210?!?
2 iamy2k 2014-09-29
I'm actually a fan of common core bc it teaches kids how to think. However, this problem is fucked.
Why? Because in the tens place, both 12 and 32 have a two. Add ten twice. Adding 5 twice was just un-necessary.
2 C_Hitchens_Ghost 2014-09-29
It seems we could all benefit from additional math classes.
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1 dddphuckwit 2014-09-29
Separating parents from children is what it boils down to.
-2 LizardKingRumsfeld 2014-09-29
Bingo, and separate teachers from frustrated students.
1 ridestraight 2014-09-29
This an 18 minute video compilation from James Corbett. There are plenty of juicy tidbits within, that point to the conspiracy aspect of this subject.
http://www.youtube.com/watch?v=d1Ubjg_o8vg
-1 OnSpeakerCrab 2014-09-29
MY BRAIN IS ON FIRE
-2 [deleted] 2014-09-29
First of all, not a conspiracy. Secondly this type of mathematics isn't designed to teach you how to get the right answer and how to get there fast. I believe it is an attempt at teaching you the concepts behind math.
I don't think they're doing a very good job, but who am I to judge, I'm no psychologist or teacher.
But I do remember this, when I was 6 I had no fucking clue why I was taking away one from the 10's place etc, I just did it because I knew that's what I was supposed to do.
-2 archonemis 2014-09-29
So, you have nothing to add to the discussion?
Okay.
-4 strokethekitty 2014-09-29
Ahh the "not a conspiracy" comment...
Common core, according to some conspiracy theorists, is designed to confuse our children in order to "dumb down america." Therein lies the conspiracy.
As for the latter part of your comment, i had no problem understanding place values. I understood thst if the number only had one digit, it was in the ones place. If it had two digits, the first woukd be in the tens place, denoting the value of ten, while the second denoted the amount of "ones". This is typically taught before arithmetic, at least in my school and upbringing.
0 conzorz 2014-09-29
Exactly. Keeping adults busy so children are continuously sent to state run education is exactly the plan.
-1 [deleted] 2014-09-29
Just to let you know, I'm no longer six but thanks for explaining place values for me...! Things are so much clearer now.
3 strokethekitty 2014-09-29
Nah i wasnt trying to be patronizing with that. I apologize if it came off that way..
I just went into detail to illustrate that the concept of place value is incredible basic and doesnt need to be supplemented with a more rudimentary explanation. Again, sorry if it came off as patronizing...
-2 ModsRCorrupt 2014-09-29
Pretty much every anti-CC argument out there. It's always made by people who aren't teachers, too. Strange...
1 strokethekitty 2014-09-29
FTFY
I was a teachers assistant in college, and was tasked to tutor fellow collegiate level students. And in my spare time, i also tutored high school students as well.
But thanks for your assumptions.
-2 ModsRCorrupt 2014-09-29
No problem. I tutored kindergarten to college math for awhile and understand why CC was implimented and how it works.
It's not for people who already know how to solve the problems, it's for students encountering the math for the first time.
1 strokethekitty 2014-09-29
Like i said, its frivolous in this case. There is no need to teach the general population of children this alternate method. It is much more efficient to teach them the place value concept when they reach subtractions.
In this method, it is akin to counting on your fingers rather than in your head. Instead of teaching concepts, they are teaching an alternative, more rudimentary, method of getting the same answer. In this way they are not teaching subtraction, but rather addition.
I understand that there is a percentage of children who have difficulty grasping the original concept of subtractions like were taught when i was in school. These kids should then be added into remedial courses to bring them up to speed, where they can teach this alternative method to them to help them.
The problem with common core is that, like in this instance, they promote "lowering the bar" by using more rudmentary practices to teach a concept when the original methods were more efficient. This hurts the general population of kids who have no problem grasping simple concepts such as place values. It even further hurts the kids who are more gifted in math.
It is geared to help the lower end of the spectrum, while holding back the advancement of the kids who dont have an issue with this. That is the problem i have with common core.
In addition, they are focusing all of this effort to change the curriculum while completely ignoring the fact that they need to really improve HOW the subjects are taught.
(And as a conspiracy theory spin to it) it is interesting how the ones who are implementing the change arent teachers but are financially tied to the companies that write the textbooks (i still have to research this claim. Ill be honest, i havent fact-checked this claim. Im only bringing it up because a couple of people are asking why this is related to r/conspiracy...)
-1 ModsRCorrupt 2014-09-29
It's more like they're trying to build a common core of learning and understanding so our children can compete in a global market (hence the name and speed of implementation). I think it would have been more efficient to stagger the introduction of it, but that's a mess teachers and students have to deal with now.
2 strokethekitty 2014-09-29
I think the more rudimentary aspects need to be reserved for the kids who need remedial direction so the majority of kids can continue learning new stuff instead of learning a backwards way of doing the same thing, while the more gifted kids should be placed in more advanced courses.
I support standardized tests and curriculums. I just dont support holding back the advancement of some kids to favor the needs of the other kids who dont grasp the material as quickly as everyone else.
As an analogy, its like having a group of ten runners. A few in the group are olympic level runners, while the majority can run an "average" of like a 9min mile, while the last few of the group have never done more walking than what is necessary to survive, let alone running.
Now, with this analogy, what common core does is it is putting everyone on the same level. But, its the couch potato's level. The majority of the class are stuck running at the couch potatos' pace, despite their abilities to go faster. The olympians have it the worst. This is where i take issue.
And again, all this effort without addressing the poor skills of the teachers. If a kid cant understand what the teacher is teaching, most of the time he is treated as stupid and the teacher never bothers to explain the material in another way.
As a kid, i would go to school with my cousins in germany while the rest of my peers had summer break. I was shocked that they had different levels of each class. They basically broke each course down to a remedial level, a normal level, and an advanced level. They all generslly taught the same material, but the remedial courses taught only what was necessary to meet the standards that the school put in place. The average levels taught applications of the material, and added in a few more in depth sessions. The advanced class were taught much more in depth about the concepts, the applications thereof, as well as the theories (if applicable). But they were teaching the same subject (be it algebra, calculus, chemistry, whatever.).
The best part was that once you were placed in a remedial course, you could move back into the normal courses once your grades improved. So, being placed in remedial courses did not make you stuck. They also didnt have that mentality that remedial course students were dumber than the others.
This is the model id like to see in america, where the kids who need help get help without holding back the advancement of the others.
0 ModsRCorrupt 2014-09-29
But CC doesn't eliminate different tiers of classrooms. Kids can still excel or fall behind.
-3 [deleted] 2014-09-29
Listen. That is actually the best way to do it when you're counting your change back to a customer. Since most of these kids will be working at a cash register in the future, I think it is teaching the perfect math skillset for their future.
2 strokethekitty 2014-09-29
The only way i can agree to what you just said is if they were teaching this with decimals. Not whole number integers.
In regards to being a cashier (which i have quite a bit of experience in) it is always best to figure out how much change they should get back first. the quickest, easiest math should be applied in this case.
Once the change is calculated, sure, figure out how many $20 bills first, then $10 bills, and so on, which is essentially using the same method as above. But All that extra shit theyre teaching to calculate the actual amount (in this case, the changed owed) is obfuscating simple arithmetic.
-2 OnSpeakerCrab 2014-09-29
Dear Oden, I hope I never have you as a cashier. I've worked nothing but retail jobs my entire life. That's not how you count change.
2 Samurai_light 2014-09-29
I knew if I typed enough of these, I would mess up. Doesn't really prove anything though. Is there a flaw in the logic? In the system? Could you do that math in your head? Other than my personal error, can you really provide any actual criticism, other than "It's different. I don't like it."?