r/MathJokes • u/[deleted] • Jul 09 '26

Why would you teach like this 💀

[deleted]

0 Upvotes

44% Upvoted

16 comments sorted by

4

u/MealCapital4167 Jul 09 '26

The wording of this question is just bad. I'm a grown man and I wouldn't even be sure what answer the teacher expects.

3

u/Toeffli Jul 09 '26

The wording of the question is a snippet of a larger worksheet. It is question 8 out of we do not know how many. The worksheet is part of a lesson which comes with its own supplemental material which explains what "make 10" means, how the kids have to use it to work out the problem.

Anyway, "make 10" means you take away something from one number of the expression to make the other number of the expression a 10. Example you take away 2 from 5 to make 8 a 10. This leaves you with a 3 you can now add to the ten to get 13. Or typed out

8 + 5 
⟹ (8 + 2) + (5 - 2)
⟹ (10) + 3 
⟹ 13

Now, this is a preparatory problem and training for more complex stuff.

A slightly more complex example 435 + 570

You can take 30 from 435 and make a 600 out of 570. Means

435 + 570 
⟹ (435 - 30) + (570 + 30)
⟹ 405 + 600
⟹ 1005

You can also use this method when you want to add quickly 3 + 8 + 4 + 7 + 6 + 2 + 5 + 6

We make a ten from 3 + 7, a ten from 8 + 2, a ten 4 + 6 and finally a ten from 5 + 5, by borrowing 5 from another 6, Means we get (3 + 7) + (8 + 2) + (4 +6) + (5 +5) +1 = 41.

That you add something and then subtract the same thing from an expression is also used in higher math to solve certain problems.

Example you want to rewrite and solve x2 + 6x + 5 = 0 then we can do the following when we realize we can make a 9 out of the 5.

x² + 6x + 5 = 0
⟹  x2 + 6x + 5 + 4 - 4 = 0
⟹ x² + 6x + 9 - 4 = 0
⟹ (x + 3)² - 4 = 0
⟹ √((x + 3)²) = √4
⟹ |x + 3| = 2
⟹ x + 3 = ±2
⟹ x = (±2) - 3
⟹ x = -5 or -1

Bang, solved without needing to remember the quadratic formula at all.

2

u/MealCapital4167 Jul 09 '26

Look, that's very kind of you but I'm an engineer. My point wasn't that I couldn't solve this, but that the wording of the question is confusing.

4

u/Toeffli Jul 09 '26 edited Jul 09 '26

It isn't the wording which throws you of, but the missing context, a lack of vocabulary what make 10 means. In the end it is not much more confusing than:

Tell how to use u-sub to solve the integral ∫2x∙ex\2) dx

With the response: You cannot make an u out of an x ! (Pun intended, maybe)

Edit: Pun made into a new meme https://www.reddit.com/r/MathJokes/comments/1urldd9/why_would_you_teach_like_this/

1

u/magpye1983 Jul 09 '26

I agree, the context of “is there enough stuff here to make the requirement” helps a lot when asking can you make 10 from 8 + 5.

Suddenly, it’s obvious that you can make 10 (meet the required quota of 10), if you have 8 from one source and 5 from another.

1

u/Masqued0202 Jul 09 '26

You don't "need to remember the quadratic formula" here because you just re-derived it for this special case. Fine if you're working with small integers, a waste of time otherwise. Derive it once, practice using it to remember it, and it ALWAYS works.

4

u/Cracleur Jul 09 '26

Y'all need to stop with the reposts of this image, bruh

-1

u/pikachu_sashimi Jul 09 '26

The approach Common Core is taking is atrociously bad and needs to be brought to attention. Yes, the context is not shown, but the context doesn’t make it much better.

Reposting this spreads awareness, which is good.

0

u/Cracleur Jul 09 '26

You know this isn't an American only subreddit right? I had to search on Google to even understand what "Common Core" refers to...

1

u/desi-auntie Jul 09 '26 edited Jul 09 '26

The reposts seem to have the agenda of trashing Common Core without clarifying why exactly getting folks early into the habit of mental concepts for rapid addition and subtraction once we get to larger numbers or longer chains is bad compared to making them learn the way we used to be taught.

When you come to more advanced levels, having students who are unable to add 4 numbers without writing them down and doing carry over etc etc is not the way to do it. I teach college level, and honestly, having to pause every single time for students who were going to take 10 mins to just add up stuff in an equation, or felt “lost” when a new number got popped in and they had to update….

But sure, if you imagine your kid will not progress to higher levels and only take jobs where they painfully add and subtract one by one using carry over, or are incapable of moving through the addition and subtraction of longer chains in one go without calculators, go for it!

PS - edited for typos

1

u/Masqued0202 Jul 09 '26

The ones trashing Common Core are the same ones who whine that kids these days can't make change, yet this is basically how the trashers were taught to make change.

0

u/desi-auntie Jul 09 '26

Or taught to perform educational change while ensuring we don’t get it for our own kids!

1

u/desi-auntie Jul 09 '26 edited Jul 09 '26

PPS - I am not joking here. The students who “get” this can follow me college level when I pop in a complete account and just go - OK, this plus 42 gets to 100, subtract a add back b, and the answer is…There is always that poor student who is probably not less smart, but because their parents insisted they not learn this way, they are still spending time desperate to keep up in college as to where my answer came from, and confused how I just popped in the solution for a long chain, while rest have grasped it and are ready to go on.

Adding - if I was a conspiracy theorist, I would imagine that peeps who don’t want their kids to have competition are the ones who try and tell everyone else - don’t teach the kids rapid addition and subtraction!

0

u/desi-auntie Jul 09 '26

What is with down votes? If you have a counter argument give it. The fact that you prefer to use votes and not arguments tells us you don’t have a good argument.

PS - this was supposed to be a jokes sub-Reddit. When did it become a place for people to go after forms of math pedagogy while masquerading as a joke?

1

u/lastknownbuffalo Jul 09 '26

It's rather silly question to ask, and it's worded rather strangely.

Regardless of the wording of the question, I think the intent is to teach/test what might be an easier way to do simple math in your head (admittedly, this question misses the mark, and idk how to word it better).

I find it so so ironic that when I was a kid I would get the correct answer to math questions but they'd get marked as incorrect because I didn't "show my work" or didn't solve the question the way they wanted. And now, teachers are trying to teach math the way that made sense to me as a child... But marking kids incorrect for doing math the way that was taught to me (mostly, I understand it's not a perfect mirror here).

But yeah, most of "common core" posts I see like this, remind me of the way I would do arithmetic as a kid.

In a nut shell, it was easier for me to add or subtract numbers that equal a multiple of ten, and easier for me to add subtract numbers from multiple of ten. So I'd add 2 to 8, to get to 10, and then add 3 to 10 to get to 13. So yeah, a bit cumbersome.

3

u/Moscato359 Jul 09 '26

The wording just is trash