Bad math teacher

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Welcome to every exam that I took in a Chemical Engineering class (transport phenomena) that I had to take… I tended to have a slightly non-standard approach to some math problems that was perfectly acceptable in every other physics/engineering class, but in this one they started subtracting points as soon as I deviated from scripture.


Perhaps some day in the future, when this math teacher has to teach a higher grade, they’ll encounter the notion that AB = BA


Being the parent of a 3rd and a 4th grader, I’ve seen similar. I think there’s a couple of points to make.

  • The teacher is working off a curriculum that presents the idea that multiplication, when first introduced, is always of the form (multiples) of (thing), or m x t. So by that definition, it’s technically incorrect to say that 5 x 3 = 5 + 5 + 5, since 3 is the thing being multiplied.
  • The idea that factors in multiplication can be swapped around (the commutative property) hasn’t be introduced yet, so the student can’t be assumed to KNOW that those factors can be rearranged to get the same answer.

That said, I would never accept my kids being docked points for answering this way, I’d be protesting to the teacher too.


What the actual fuck?

Unless there is some other instructions not on the sheet, I don’t get it.

Also, in before Common Core bitching.


Once I read AB = BA, an ABBA track started playing in my mind, which promptly tried to figure out a ACSII emoji that fit the equation: “ha! it’s a perplexed cat!”


Assuming an abelian group.


I’m reminded of the time I lost 10 points in a chemistry lab report for saying a chemical burned with a “yellow-orange” flame, rather than the teacher-approved “orange-yellow”. Yes, it was entirely subjective because we weren’t using spectroscopes to observe emission/absorption lines. No, she didn’t care. Thank god nobody in our class was colorblind!


The teacher may very well have good reason to be docking points. It could very well be that they are teaching the kids that they are to read the multiplication problem as “5 Groups of 3 equals”. This may be to prepare the properly read a division problem in the future.

Furthermore the second one might be to prepare the child to correctly print out matrices in their future more advanced math classes where a 4x6 matrix is very very different then a 6x4 matrix.

Lets not jump to conclusions now.


You Will be Assimilated. Resistance is Futile.


This is what I have to look forward to. My kid’s in 1st right now. So far, our first-year-teaching-full-time teacher hasn’t made any robotic, must-follow-script-exactly boneheaded mistakes like this on his math homework. The boy is getting stars for just turning them in on time and complete. Correct answers are just the icing on mom’s supervision cake.


One of my anatomy teachers also taught math. Our textbook described a concussion, or one form of it, as a rupturing of blood vessels in the brain and added that a concussion may be described as “a brain bruise”.

It still rankles me that I used the longer description on a test when asked to define a concussion and got docked points because my teacher crossed that out and wrote “BRAIN BRUISE!” in angry red letters. And at the time I thought, hey, I guess that’s why you mostly teach math. You can’t handle questions with more than one right answer.

Granted #notallmathteachers


Except the student actually demonstrated that they did know!


Borg math: 1 + 1 + 1 + 1 + 1 = 1


Shocking, the notion that a child in first grade trying to accomplish homework and actively participating could be seen as more important than a seven year old getting every answer correct for a perfect grade. (ie their parents doing their homework for them)


My daughter got docked a mark on a math test in grade 2 during a probability unit because she categorized the statement “you will go to sleep tonight” as “likely” instead of “certain”. I told her that I wasn’t going to intervene but she was welcome to protest to the teacher. The teacher refused to change the grade. My husband let her stay up all night the following Saturday. She felt pretty smug when the sun came up the next day.


Actually the common core (at least the one my kids are taking) is very focused on showing many many ways to come at and solve a problem. More than I’m am even familiar with, so I end up learning some new techniques or just scratching my head as to “why are you doing it that way? Must be this ‘New Math’” :smile:


You know…I have a 9th grader, 7th grader, and 2nd grader. So I have seen this sort of thing before. When I was a kid, getting the right answer was the important part, not how you got it (assuming no cheating). Today, its all “SHOW YOUR WORK” because they are teaching the methods…I get that.

HOWEVER…this one I have a problem with. In the first problem he/she corrects the kid to use the primary integer in the columns and secondary integer in the row for restating the equation in a repeated addition strategy. But why in the hell is the expectation the opposite for the array strategy!!! He/She then corrects the kid to qualify the secondary integer in the columns and primary in rows.

Pick a methodology for applying the strategies.


Points and grades on this level of education are just (even more) stupid (than grades and points later on).
This was an opportunity to start a conversation about the “why” here, and by just docking points they’ve killed that chance. A shame, that is.
Why not just take this as the time to teach the commutative property (since it’s just come up!)?

I’ll also be clear:
This is not the failing of “new math” or a “common core” thing- this is a teacher throwing away a chance to teach.


I am actually PRO Common Core.

Nearly every criticism I have seen about CC has nothing to do with it.

Even in your example, that is just the new curriculum that the educators are coming up with on new ways to teach kids math. CC doesn’t actually say you have to teach that way.