Second grade 'estimated' multiplication

[Porsche-O-Phile]

There are no absolutes. Not even this.

[Rearden]

I saw a few minutes of that TV show 'Are You Smarter than a Fourth Grader'. I must confess that I got a question wrong. Maybe the stuff they teach in grade school is a waste of time and not applicable to the adult real world. Just a theory.

[Tervuren]

Originally posted by #39
I guess that's my point, that the teacher is not having the students complete the equation.

Maybe this is just the first step, and she will introduce the second step (adding the 2 x 6 = 12 to 360) tomorrow.

I just hated to see her write 360 as the answer to 62 x 6, when she is quite capable of figuring out the correct answer. I understand your points about breaking the problem down into more workable chunks. I'll follow up on how the lesson progresses.

You can't just expect a school to "educate" your children, perhaps a little time explaining estimation would of been in order. Especialy if it isn't covered today.

[ckissick]

It's the best approach to doing math, that is, multiplying from left to right instead of right to left. Those guys on TV who can multiply large numbers in their head do so by the method being taught to your 2nd grader, except they add the 12 to get 372.

For example, do this in your head:

563 X 6

say: (500+60+3) X 6

so you get:

500 X 6 = 3000
60 X 6 = 360 (this one looks familiar)
3 X 6 = 18
Equals 3378

It's not that hard. I have a book called Secrets of Mental Math by Arthur Benjamin and Michael Shermer that's pretty fun. With practice most people can learn to do pretty amazing things with math.

Let's hope the teacher goes the next step and gets the kids to add the 12 later on.

[nostatic]

estimation is an important skill for real scientists. It is not a "liberal arts plot." Hate to burst your bubble...

If they asked for 2 significant digits, 360 actually is the right answer

I can't tell you the number of times I had students give dumbass answers because they did not understand orders of magnitude or approximation. A good science student should be able to look at a complex equation and give you a quick guestimate of the answer.

[ckissick]

Originally posted by nostatic
estimation is an important skill for real scientists. It is not a "liberal arts plot." Hate to burst your bubble...

If they asked for 2 significant digits, 360 actually is the right answer

I can't tell you the number of times I had students give dumbass answers because they did not understand orders of magnitude or approximation. A good science student should be able to look at a complex equation and give you a quick guestimate of the answer.

This is one of the best lessons I learned in science. Our first quiz in Geophysics had questions like, "How many ping-pong balls are there in a suitcase?", and "How many piano tuners are there in New York City?" We were only to come up with orders of magnitude.

It drives me crazy when I see a geologist give data with a few significant figures, thinking they matter, when an order of magnitude is about as accurate as you can possibly get.

This same argument can be used to argue the merits of computer models that predict climate scenarios over the next 100 years.

[red-beard]

2 words: Slide Rule

[ZOO]

Originally posted by sammyg2
BTDT, heped my daughter with her homework and tried to explain to her that what was in that book was not real math, it was a travesty. typical of liberal arts majors trying to polute what is supposed to be a pure science.
2 x 2 = 4, how does that make you feel? Asshats.

opps, I hope I didn't offend the overpaid underworked part time workers we call teachers, they might go on strike again.

You know, if you think teachers are overpaid and underworked, you could always join them. I understand that most states are desperate for people to teach.

Anyone who thinks that probably votes for the very legislation that destroys public faith and confidence in a public education system for all. Sad.

[kach22i]

Originally posted by #39
'estimated' multiplication.

"No Child left behind", the kids are being taught to pass a multiple choice test, all they have to do is get in the ballpark.

Thank you GWB.

EDIT: If you asked me that at the start of 4th grade, I would of needed paper and pencil because I was taught to stack the numbers, not exactly something you can visualize with some one barking in your face - it happened.

Using lazy math, 60 x 6 = 360 because 6x6=36 and you add a zero. Doing more lazy math 2x6=12. Doing simple addition 360 + 12 = 372. It's the scenic route but it works without paper and pencil on the fly.

62 x 6 = 372

Strange but there might be an upside to this all

[Moses]

Originally posted by mattdavis11
I do it all the time when I have to do it in my head. Seems easier sometimes to multiply 6x60 and add on the twelve to get 372.

If I was asked what 15x17 was, it's easier knowing that 15 squared is 225, I then add 30 to it to get my answer.

Maybe that's the approach they have in mind, only using your mind.

Exactly. Math is a language. Like any other foreign language teaching someone the mechanics of the language is different from teacing them to think in a new language.

The way Matt is doing the calculation in his head is evidence of "fluency with numbers". That's what people do when they are really comfortable with numbers.

[M.D. Holloway]

Thats the way We are trying to teach Our Son as well. He is real good at math and has chosen it to be his strength (mainly because he really wants to be great at a particular school subject and he really struggles with reading).

Other 'tricks' We use along the same lines with big number additon and big number subtration, not unlike the distribution technique discribed.

Kids love 'tricks'. He feels like he has insight into another world no other kid does. Maybe it is a form of empowering, who the ***** knows.

At the end of the day as long as he has his math, spelling and reading comprehension down I think that will be great.

[daepp]

This fuzzy estimation is in the private schools too.

The fact is, we all learned estimation by first learning to figure the correct answer. It is ridiculous to teach estimation. I have had to deal with it with all 3 of my children, and my youngest, my son, learned from his sisters not to ask dad about is cuz it sets him/me off.

I can just imagine me telling Sister Bridget that I was going to estimate my math answer. I can feel the ruler even now!

[Spede]

http://humancalculator.com/

[KFC911]

I've always tested in the top .1 percentile in math, and I use techniques like this all the time. If you are comfortable with numbers, it's almost second nature imo. I use this technique a LOT if I'm mentally adding/subtracting outside of the base 10 system (i.e. Hexadecimal...you computer geeks know what I mean).

[SlowToady]

Originally posted by KC911
I've always tested in the top .1 percentile in math, and I use techniques like this all the time. If you are comfortable with numbers, it's almost second nature imo. I use this technique a LOT if I'm mentally adding/subtracting outside of the base 10 system (i.e. Hexadecimal...you computer geeks know what I mean).

Second graders are comfortable with numbers?

I still think kids should be taught mathematics properly before jumping around to tricks and what not. Learn it properly and learn it well, and learn the tricks later when you'll actually know why they work.

Just my opinion, I may be wrong...who knows. But, it is widely known that math and science scores are down across the US for quite some time...and maybe teaching methods like this are the reason. (Or, hell, maybe they are the solution...whatever, I don't know.)

Oh and by the way....you guys need to stop blaming NCLB on Bush. I know it's the cool thing to do, especially for those that don't know what they are talking about, but largely the same legislation has been around for quite awhile; Bush made some changes and gave it a new name. BFD.

[kach22i]

Originally posted by SlowToady
Oh and by the way....you guys need to stop blaming NCLB on Bush. I know it's the cool thing to do, especially for those that don't know what they are talking about, but largely the same legislation has been around for quite awhile; Bush made some changes and gave it a new name. BFD.

That was me, thank you.

Bush instituted a similar program in Texas while acting as the Governor. He and his cronies fooled a lot of people into thinking it improved education and set a higher standard. What it really did was to put pressure on weaker students (not qualified as retarded - just low) and their very often poor parents (including many migrants and illegals - don't cheer to loudly please) to drop out, and therefore not to be counted in the average anymore.

They are also known as the children Bush left behind.

[Rearden]

Originally posted by kach22i
That was me, thank you.

So public schools shouldn't be measured and held accountable for poor performance? Let me guess: you don't have any children in public school.

[Flatbutt1]

OK I must pick a nit. Some posts are talking about Mathematics but I consider the original post to be about Aithmetic. I consider them to be different. I'm just sayin'

[expat]

Some of you are mentally challenged if you don't understand that grouping as per the original exercise is completely logical and works for much higher order thinking in more complex tasks later in life.

I honestly am amazed by the lack of intelligence a few of you are demonstrating here. Don't you ever approximate when you go to your local hardware to buy some timber, rubber tubing, paint to cover a wall. That's exactly what the child is doing; approximating and eventually calculating and comparing. I am sure the teacher is not going to check an answer of 360 as being the correct answer for calculating. Its estimating - you know that thing you do when you go to the hardware store.

The initial question was valid - no problems there. It was just clarification that was needed and answered.

The assinine comments about teachers by SammyGspot are typical rantings from him. Best just to ignore. (yes I did mean ss)

[mattdavis11]

Originally posted by kach22i
That was me, thank you.

Bush instituted a similar program in Texas while acting as the Governor. He and his cronies fooled a lot of people into thinking it improved education and set a higher standard. What it really did was to put pressure on weaker students (not qualified as retarded - just low) and their very often poor parents (including many migrants and illegals - don't cheer to loudly please) to drop out, and therefore not to be counted in the average anymore.

They are also known as the children Bush left behind.

You're so full of ****. hehe
These activities were/are held after school, and the kids could benefit, and the teachers could get paid more. It was a result of the fight for teacher pay raises, increase the low performing schools type of deal.
Some districs have gone private contract for the extended education. (NCLB) Local control, we like it that way in Texas.

You can't fix pub ed by throwing more money at it. IMHO, the pub ed lobby is the most disorganized bunch I've ever seen.