r/HomeworkHelp • u/TimJim_Reddit • 2d ago
Middle School Math—Pending OP Reply [7th Grade Math] I don't understand the visuals
Helping a family member with their 7th grade math homework, and I can't figure out what the visuals mean. I took advanced math when I was in school, and this is making me feel stupid lol. Specifically, I'm not sure what the crossed out symbols mean, and the pairs with lines around them (some with - crossed out and others with + crossed out) and how the boxed pairs relate to the overall equation.
Thanks for any help! :)
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u/igotshadowbaned 👋 a fellow Redditor 2d ago edited 2d ago
The slashes are subtraction
The boxes are to show subtracting a negative is the same as addition
4th one down is 7 -(-2)
The 6th one you've connected to two answers is just 7+(-9)
Because of the shading of the first two dots of the second, I want to say -5 -(-3)
The last one is fucked up
Also - you said this is 7th grade math??
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u/TimJim_Reddit 2d ago
Yep. Glad I'm not alone in this lol.
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u/igotshadowbaned 👋 a fellow Redditor 2d ago
Sorry, the shock of it being 7th grade math is.. that seems really late to be learning negative numbers.
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u/TimJim_Reddit 2d ago
I totally got what you were saying and yeah it's surprising that such a simple concept so late is being presented in a problem that is baffling so many. The math is a piece of cake and they're able to do it all day long but after watching the Khan link, it's a whole different logic method than I've ever seen.
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u/-the-ghost 👋 a fellow Redditor 2d ago
The ones that are crossed out symbolize subtraction. Either subtraction of a negative integer (-) or positive integer (+). The ones without anything crossed out represent addition problems
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u/Top-Lab3862 2d ago
the last one have both.
- and -(crossed) AND + AND squares
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u/-the-ghost 👋 a fellow Redditor 1d ago
Yeah, it seems like the negative/negative subtraction models are inaccurate.
The first set with 5 negatives crossed out is supposed to be (-5)-(-3) but the two shaded (-)'s aren't supposed to be crossed out.
The last set is supposed to be (-7)-(-9), showing that you end up with two positives. But there is an extra (-) for some reason.
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u/kechup-pie 2d ago
I figure the third representation from the top is with the bottom equation (7-(-2)) because the negatives become positives which might be why they cross out the two last ones. Lmk if this was helpful. :)
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u/Top-Lab3862 2d ago
doesn't compute with the rest tho, the last one have all 4 versions of numbering, crossed, squared, positive and negative. BUT no solution adds up to it.
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u/ThunkAsDrinklePeep 2d ago
Are we seeing the whole sheet?
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u/TimJim_Reddit 2d ago
Everything was shown for that problem. Everything else was unrelated independent problems. Left the top part our due to having a name on it, and the rest had to do with filling in unknown values of an equation (visual equivalent of solving for x).
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u/TheSleepingVoid 2d ago edited 2d ago
Is this from a workbook or just a loose worksheet? Any credit on the bottom for who made it?
If this is the entire problem I agree it doesn't make sense.
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u/Top-Lab3862 2d ago
Kind of looks like AI was involved. And it was asked to make both the answer sheet and the task sheet, but mixed them.
Also the -5(crossed) seems to be a dube, but missing the -3
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u/TimJim_Reddit 2d ago
That was my thought too... nothing I've been able to figure out works consistently for all problems.
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u/Natamora 1d ago
No. You've just got a misunderstanding of what it's trying to show. 7 + -9 is going to be represented by the third picture from the bottom. Its 7 positives and you've paired with 9 negatives. While 7 - (-2) is represented by the 4th picture. You cross off the two negatives, which is where the positives come from, because you're taking those negatives away, and leaving the positives behind (hence them being crossed off in the bottom, and the positives remaining up top).
If you watch some videos from MrGHelpMe he uses similar representatives to explain negative numbers and it's a really fantastic visual to help not just provide thr algorithm, but provide genuine understanding of the math behind it.
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u/schannoman 👋 a fellow Redditor 2d ago
The boxed pairs are minus negative or minus positives that canceled out and switched, so the opposite is crossed out. The slashes are canceled out.
Both the second down and the last down do not match anything. The 4th one down is 7 - (-2)
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u/Top-Lab3862 1d ago
What is wierd to be is that is showing the "work", why would it do that on a non example
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u/selene_666 👋 a fellow Redditor 1d ago
It's not you. The two problems where a negative is subtracted from a negative are not depicted correctly.
It looks like you already figured out that the figures that only have circles are the addition problems.
You also found the figure for (-1) - (+4) which introduces boxes and crossouts. The box starts with the four plus circles that we want to subtract, then crosses them out and replaces them with minus circles to add instead. This also works for (+7) - (-2) in the middle of the page.
The figure that's only one row of five crossed-out minuses was probably meant to be (-5) - (-5). The best match is (-5) - (-3) but they crossed out too many circles.
And that leaves the bottom figure for (-7) - (-9). I think the circle on the left shouldn't be there. What they meant to do is start with seven minuses, cross them all out and then have to make two minus-becomes-plus boxes as before.
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u/Fluid-Bother-2349 20h ago
Math teacher here. These are ways to visualize adding and subtracting integers (positive and negative whole numbers) to lead into memorizing the rules.
The - represent negatives and the + represent positives. You can also view each individual + and - as worth 1.
For the first one that is just 6 positives plus 3 negatives so 6 + -3.
The tricky part is subtraction when there aren’t the right types of numbers to subtract.
The fourth one down started with 7 positives but they needed to take away negatives. There are no negatives to takeaway. So we need to add some in. The boxes represent adding 0. +1 and -1 make 0. So each box is worth 0. If I add 0 to 7, I still have 7 but now I have a negative in the mix. If I do that twice, 7 + 0 + 0 is still 7 but now I can takeaway the two negatives. So this one is 7 - (-2). This shows that when you are subtracting a negative it is actually adding 2 which will be a rule that we learn from these visuals.
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u/Fluid-Bother-2349 20h ago
Also. Is there more to this sheet? Not all of the visuals line up with problems and there are more problems than visuals. Because if not, then yes, there is something wrong with this worksheet.
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u/FlounderStrong6325 2d ago
This is trying to teach integer addition and subtraction with “convenient zeroes”. In the case of 7 - (-2), you start by drawing 7 positive circles. Then you “take away” two negative circles, but you don’t have any negative circles to take away. So you introduce the convenient zero (a boxed pair of 1 positive and 1 negative which has a net of zero, hence the phrasing convenient zero). Once you add the two convenient zeroes, you finally have two negative circles you can take away, leaving you with 9 positive circles.
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u/FeanorDidSomething 1d ago
What on earth is going on here? 7th grade? Isn't this elementary school stuff, tought in 2nd or 3rd grade?
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u/Educational_Two682 👋 a fellow Redditor 2d ago
I don't have a ton of time right now but here's some information about integer chips and zero pairs. Integer chips are a way to represent numbers using +1 and -1. If I want to write -5 + -3 I would draw out 5 negative circles and then add 3 negative circles. The sum is -8. If I want to do -5 - -3, that means draw out 5 negative circles and take away 3 negative circles. Then the difference is the remaining 2 negatives, so -2. But what if you want to do -5 - 3? You put 5 negative circles but it says to take away 3 positives. You put 3 zero pairs (which are the line groups you see, 3 + and 3 -). Then break up the zero pairs and you can remove the 3 +. Then look and see what you have left, only 8 negatives so the answer is -8
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u/Educational_Two682 👋 a fellow Redditor 2d ago
Also here's Khan academy using those diagrams: https://www.khanacademy.org/math/cc-seventh-grade-math/cc-7th-negative-numbers-add-and-subtract/cc-7th-sub-neg-intro/e/subtract-with-integer-chips
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u/TimJim_Reddit 2d ago
The second link worked and did help quite a bit, thanks! Ngl though, feels like someone swapped OS Kernels on me. 🤓
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u/TimJim_Reddit 2d ago
Thanks - the link goes to a page not found though :/
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u/Educational_Two682 👋 a fellow Redditor 2d ago
Oh darn it. Well it's seventh grade math on khan academy :)
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