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How Japanese Kids Learn To Multiply

magicalmaths.org

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Re: How Japanese Kids Learn To Multiply

#71

Post by derleth »

talmand wrote: post #25
hemancuso wrote: post #10

This does not teach you multiplication as much as it teaches you a trick to get the result of multiplication. I doubt anyone is transferring this abstraction that results in the answer into something they can do in their head or extend on paper to larger numbers. Teach kids to open the calculator app on their phone rather than to do this. No fast way to learn multiplication other than to practice it.

I agree, I don't see how this actually teaches how multiplication actually works. It's a clever method to avoid solving the problem the classic way of using a memorized multiplication table and breaking down the problem into smaller segments. I don't even see how this saves you time once you get up to speed on either method. The only difference is that with my old school way I can explain to you why I get the answer…

> I don't see how this actually teaches how multiplication actually works.

[snip]

> It's a clever method to avoid solving the problem the classic way of using a memorized multiplication table

Do you think multiplication actually works by means of a multiplication table?

Re: How Japanese Kids Learn To Multiply

#72

Post by DrDreams »

boredguy8 wrote: post #57
symmetricsaurus wrote: post #6

The videos only show the technique using small digits. For the larger digits this method quickly becomes cumbersome. Latttice multiplication is much better for large numbers and deals with a lot of the carrying of overflowing digits which occurs in both normal and "Japanese" multiplication. http://www.youtube.com/watch?v=cijuPxHgZAA edit: spelling

yes, there are no '57 * 86' examples, which would be counting intersections for quite some time.

You guys are exactly right. This method is bullshit snake oil for weeaboos as it involves counting up to the product of every single product, which is tedious and error-prone. It is safe to label anyone who praises this method as a math-hipster or pretender who only likes the warm fuzzy feelings of simulated simplicity rather than actual, real, pragmatic, useful value. They should be fucked gently with a chainsaw.

Re: How Japanese Kids Learn To Multiply

#73

Post by zwieback »

tokenadult wrote: post #9

The more important difference between mathematics education in Japan and mathematics education in (say) the United States is how hard the problems are and the encouragement to pupils in Japan to try to figure things out for themselves. I put instructional methodologies to the test by teaching supplemental mathematics courses to elementary-age pupils willing to take on a prealgebra-level course at that age. My pupils'…

Regarding the "dark arts" quote: not my experience. I'm not present at my kids lessons but the homework indicates a wide variety of approaches, methods and applications are used. The math textbooks are much more interesting and varied than the ones I had as a kid.

Re: How Japanese Kids Learn To Multiply

#74

Post by talmand »

derleth wrote: post #71
talmand wrote: post #25

Earlier quoted context omitted.

I agree, I don't see how this actually teaches how multiplication actually works. It's a clever method to avoid solving the problem the classic way of using a memorized multiplication table and breaking down the problem into smaller segments. I don't even see how this saves you time once you get up to speed on either method. The only difference is that with my old school way I can explain to you why I get the answer…

> I don't see how this actually teaches how multiplication actually works. [snip] > It's a clever method to avoid solving the problem the classic way of using a memorized multiplication table Do you think multiplication actually works by means of a multiplication table?

No, if that's how I came across then that's not what I intended. Although, I feel you're a bit selective in your snips in an effort to make some kind of point. I know how multiplication works, but the memorization of the table speeds up the process. I was simply trying to say that this method was not much different, nor more superior, than table memorization.

My comment about not teaching how multiplication works is aimed at the statement made that this method is how Japanese students learn to multiply, as in the title of this thread.

Re: How Japanese Kids Learn To Multiply

#75

Post by zwieback »

frouaix wrote: post #53

By the way, if you or you children need a quick and easy way to practice mental calculations, find an implementation of the game http://en.wikipedia.org/wiki/Des_chiffres_et_des_lettres on your phone.

Thanks for bringing back memories of ski vacations in the French Alps. We couldn't understand most of the stuff on TV but loved this show.

Re: How Japanese Kids Learn To Multiply

#77

Post by tsahyt »

ricardobeat wrote: post #34

Still quicker to do the math in your head: 123 * 321 321 * 100 = 32100 321 * 20 = 6420 321 * 3 = 963 ----- 39483 You just need to know the times table and keep a little stack in your head :)

Keeping the stack has always been the problem for me. At least for larger numbers. Luckily, there's RealCalc on Android which is by far the best calculator app I've ever seen.

Re: How Japanese Kids Learn To Multiply

#78

Post by chubbard »

This method is also referred to as Mayan Multiplication which isn't necessarily exclusive to Japan or a technique the Japanese invented. It's not Mayan either, but just a neat technique to make multiplying numbers easier. Although it might be hard to perform in your head this way.

The babylonians, egyptians, and romans had their own techniques because multiplication by hand is not easy, and it's time consuming. Techniques like these enabled those civilizations to build wonderful engineering marvels. The point is these techniques don't violate math or subvert teaching math because it's not the same thing.

This subject was originally called arithmetic when I was in school which was different than math. Arithmetic was the rudimentary techniques for how numbers were added/subtracted/multiplied/divided where math was word problems that required you know arithmetic to solve but also required logic and abstraction. So yes arithmetic != math, but that doesn't mean teaching arithmetic is NOT useful. They are different concepts that are related, but not the same.

I think this is perfectly fine to teach someone this. The whole computation isn't math argument is a misplaced. We're talking about 2nd or 3rd grade students. They'll learn math at the higher levels again.

Re: How Japanese Kids Learn To Multiply

#79

Post by jff »

tsahyt wrote: post #77
ricardobeat wrote: post #34

Still quicker to do the math in your head: 123 * 321 321 * 100 = 32100 321 * 20 = 6420 321 * 3 = 963 ----- 39483 You just need to know the times table and keep a little stack in your head :)

Keeping the stack has always been the problem for me. At least for larger numbers. Luckily, there's RealCalc on Android which is by far the best calculator app I've ever seen.

I'm a fan of Droid48. It emulates a HP-48, so it displays the stack on-screen and has advanced capabilities like graphing if you need them.

Re: How Japanese Kids Learn To Multiply

#80

Post by pbhjpbhj »

Ntrails wrote: post #24
Jabbles wrote: post #11

Great. Now do it for 79*86.

realistically all this or any other process is doing is expansion and taking advantage of the commutative nature of multiplication. (70 + 9)x(80 + 6) 70x80 + 9x80 + 6x70 + 6x9 56(00) + 72(0) + 42(0) + 54 Guess what - long story short you need to know your times tables. I don't see how the lines method is any easier than long multiplication, which in itself is not hard with a little time and explanation. If you can us…

* It's not backslash!

I think you can only do * with an unpaired * terminator * ?

I think you can only do * with an unpaired * terminator ?

I think you can only do xx with an unpaired xx terminator xx ?

[that line is this with no spaces around :I think you can only do x * x with an unpaired x * x terminator x * x ?

Nope, looks like as long as it's spaced from the prior/next character then it doesn't cause italicisation.

Help says: "Text surrounded by asterisks is italicized, if the character after the first asterisk isn't whitespace."

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