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how would you guys do 28+14

how would you guys do 28+14

how would you guys do 28+14

just memorize

That still feels weird to me

The way I'd think about it is I know 7 + 7 is 14 so 7 + 8 is 14 + 1

I think "7+7=14, then add 1, so 15".

I mean I don't think 7+8 is difficult in my head but does this method scale up? So like if I had 378+987 can you use this method? I could see the value in it then.

That's what I do, too. But how do you know 7+7-14? You probably memorized it, it's not easy to imagine 7 items + 7 items. It is easy to imagine 7+x=10.

That's what I do, too. But how do you know 7+7-14? You probably memorized it, it's not easy to imagine 7 items + 7 items. It is easy to imagine 7+x=10.

I think this Common Core method gets easy too much hate. Making everything revolve around 10, 100, etc. makes mental math much easier.

However you can tell this is garbage by how confusing the instructions are. If you make these Common Core methods as confusing and unintuitive as possible then there is literally no benefit to them. Its like the teachers dont actually understand what they are doing or they want the students to fail

Because 7+7=7*2 and we learned something called the Multiplication table in school.

it is called the times tables 7x2=14 or 7,14,21,28,36,42,49,56,63,70,77,84,91,etc

It's a mental math trick that you should learn if you don't know.
7+8 is hard to do in your head, but 8+2+5 is easy because you can group 8+2=10+5=15.

I think the teacher made a mistake and looked back at the 7 instead of the 8.

Yeah, you guys shouldn't be commenting at all on education. This is a class teaching basic addition, they're not going to learn their times tables before they learn 7+8. And, again and again, we're trying to move away from pure rote memorization and towards understanding concepts.

7+8 is hard to do in your head? It's 15. It's always 15.

You're missing the point like the boomers sharing this pic on facebook would. You know 7+8=15 because you were a good little student in elementary school who memorized it. But the principle of getting the equation into base 10 exponentials goes beyond single-digit numbers. So although you memorized 7+8, you never memorized what 187+179 is. So to do the mental math quickly, a great trick is to do something like "187 + 13 = 200. 179 - 13 = 166. So the answer is 200 + 166 = 366". Because it's much much more intuitive to add 166 to 200 (a multiple of 10 / 100) then it is to add 187 to 179.

You can do something similar by taking advantage of 10's in multiplication and division. If someone asks you how many times 7 goes into 217 you could draw up a division bracket and work it out as you learned to do in 3rd or 4th grade. Or you could mental math it by doing something like "7*10=70. 70*3=210. So 7 goes into 217 31 times." The point is to use 10's as much as possible without having to memorize things. And it only looks really silly here because the examples shared on facebook are always elementary problems that you memorized. When you can't memorize them then you see why they're more useful.

As an aside here's a fun fact - why do almost all humans in almost every century use base 10? The answer is simple. It's because humans have 10 fingers. So people counting on their fingers and grouping things into sets of 10 is human nature. Incidentally we also have 10 toes but people are probably counting with their fingers more than their toes. But if we had 12 fingers we'd probably have a base 12 system and this discussion would be all about how stupid Common Core is trying to teach "making a 12" to kids now. Thinking about it that way kind of helps elucidate the point behind focusing so much on 10 and why an equation having 10s makes the math much more clean and intuitive.

https://i.redd.it/slduddmgwgha1.jpg

You're missing the point like the boomers sharing this pic on facebook would. You know 7+8=15 because you were a good little student in elementary school who memorized it. But the principle of getting the equation into base 10 exponentials goes beyond single-digit numbers. So although you memorized 7+8, you never memorized what 187+179 is. So to do the mental math quickly, a great trick is to do something like "187 + 13 = 200. 179 - 13 = 166. So the answer is 200 + 166 = 366". Because it's much much more intuitive to add 166 to 200 (a multiple of 10 / 100) then it is to add 187 to 179.

You can do something similar by taking advantage of 10's in multiplication and division. If someone asks you how many times 7 goes into 217 you could draw up a division bracket and work it out as you learned to do in 3rd or 4th grade. Or you could mental math it by doing something like "7*10=70. 70*3=210. So 7 goes into 217 31 times." The point is to use 10's as much as possible without having to memorize things. And it only looks really silly here because the examples shared on facebook are always elementary problems that you memorized. When you can't memorize them then you see why they're more useful.

As an aside here's a fun fact - why do almost all humans in almost every century use base 10? The answer is simple. It's because humans have 10 fingers. So people counting on their fingers and grouping things into sets of 10 is human nature. Incidentally we also have 10 toes but people are probably counting with their fingers more than their toes. But if we had 12 fingers we'd probably have a base 12 system and this discussion would be all about how stupid Common Core is trying to teach "making a 12" to kids now. Thinking about it that way kind of helps elucidate the point behind focusing so much on 10 and why an equation having 10s makes the math much more clean and intuitive.

This post reminded me why I almost failed every math class since middle school... God, I'm an idiot lol...

You're missing the point like the boomers sharing this pic on facebook would. You know 7+8=15 because you were a good little student in elementary school who memorized it. But the principle of getting the equation into base 10 exponentials goes beyond single-digit numbers. So although you memorized 7+8, you never memorized what 187+179 is. So to do the mental math quickly, a great trick is to do something like "187 + 13 = 200. 179 - 13 = 166. So the answer is 200 + 166 = 366". Because it's much much more intuitive to add 166 to 200 (a multiple of 10 / 100) then it is to add 187 to 179.

You can do something similar by taking advantage of 10's in multiplication and division. If someone asks you how many times 7 goes into 217 you could draw up a division bracket and work it out as you learned to do in 3rd or 4th grade. Or you could mental math it by doing something like "7*10=70. 70*3=210. So 7 goes into 217 31 times." The point is to use 10's as much as possible without having to memorize things. And it only looks really silly here because the examples shared on facebook are always elementary problems that you memorized. When you can't memorize them then you see why they're more useful.

As an aside here's a fun fact - why do almost all humans in almost every century use base 10? The answer is simple. It's because humans have 10 fingers. So people counting on their fingers and grouping things into sets of 10 is human nature. Incidentally we also have 10 toes but people are probably counting with their fingers more than their toes. But if we had 12 fingers we'd probably have a base 12 system and this discussion would be all about how stupid Common Core is trying to teach "making a 12" to kids now. Thinking about it that way kind of helps elucidate the point behind focusing so much on 10 and why an equation having 10s makes the math much more clean and intuitive.

Because 7+7=7*2 and we memorized something called the Multiplication table in school.

The question is when would these students use this shit in real life. Just teach them regular math.

how would you guys do 28+14

1.OA.C.6 Add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 4 = 13 3 1 = 10 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13).

2.OA.B.2 Fluently add and subtract within 20 using mental strategies.2 By end of Grade 2, know from memory all sums of two one-digit numbers.

1.0A.B.3 Apply properties of operations as strategies to add and subtract.3 Examples: If 8 + 3 = 11 is known, then 3 + 8 = 11 is also known. (Commutative property of addition.) To add 2 + 6 + 4, the second two numbers can be added to make a ten, so 2 + 6 + 4 = 2 + 10 = 12. (Associative property of addition.)

So whether the student did 5+2 or 2+5, I think I'd mark it right, and have that discussion about how both answers are correct, but that one might be preferred since it positions the 2 and 8 together.

I think people are giving the teacher too much credit

No one is giving the teacher any credit. Everyone (including the user you quoted) said the teacher made a mistake while grading