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Why don't we use the math we learn in school?

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Re: Why don't we use the math we learn in school?

#121

Post by eternityforest »

jfengel wrote: post #120
eternityforest wrote: post #54

Earlier quoted context omitted.

Maybe they should get engineers to teach math courses the way they wish they had been taught them, rather than math people who sometimes still seem to think we will be doing this without a calculator?

Engineers have specialty interests. I'd just as soon have it taught by a home economics department, or at worst an MBA. Things everyone should be able to do: read a bill, allocate a budget, estimate how much food to buy for 2 people versus 10 people, plan for retirement, maybe convert a recipe from metric to imperial units. Perhaps get a shop teacher. Let the future STEM majors learn the rest in their classes. It tak…

Giving STEM majors a head start is helpful, and a lot of those things aren't primarily mathematical.

I'm not sure what math you need to read bills in the age of specialty apps. I can't remember the last time I needed to do any arithmetic without my phone.

Estimating how much food to buy for 2 people requires understanding nutrition science, whether all your guests ate at all today, how much space you have to store leftovers, etc.

The only math I can think of is jus t multiplying by number of guests, But then you might have kids or people with dietary restrictions and now half your planning is just individual person by person stuff.

Math won't really help you plan a budget either unless you know all the finance specific stuff, or enough fairly advanced general math that it's just all obvious to you.

There's way too much estimation of real world stuff and most of the controllable expenses(for an average poor person) are impulse fast food orders and such that they already know are costing a ton.

I'm not sure trust an MBA to teach... anything about economics. They are way too high on their positive mindset business optimism attitude to really understand that the cost of getting Starbucks actually is important.

A lot of the "Useful real life math" is stuff that people won't use anyway, either because an app does it, or because retirement is later and doordash is right now. Is math actually the most effective tool to make someone want to stop that?

Re: Why don't we use the math we learn in school?

#122

Post by TristanBall »

I'm 43, I got taught fractions in primary.. wait let me do some math, about 32 years ago. 1

I seem to recall fractions being presented as the necessary "old way" before they taught us decimals, but maybe that was just me.

I had no idea* about the multiplying fractions thing to solve the example. 2. Maybe I was tought it, I guess I probably was, but it also just about the last time the curriculum touched on fractions at all, at least until I dropped out at year 10 ( 2 years early ). Maybe those last two years are a fraction filled bonanza.. but I suspect not.

So unless I'm super interested on my own, its quite possible it's decades before I find a use for it?

Just how effective do you think 5 hours a week for two 4 week periods 30 is at instilling knowledge - especially over decade timeframes.

The example is actually a good one, because finding a fraction of a fraction of a cup is the kind of thing you might need when reducing the size of a recipe.. but it also demonstrates the problem... Close enough is good enough.. I can tip out part of the measure and eyeball it anyway - and can do so without thinking about it at all! And I'm cooking.. I'm doing rough measures and adjusting as I go anyway..

If math concepts aren't revisited throughout schooling, with concrete uses how does anyone retain this stuff? ( Of course, I'm a drop out with a notoriously bad memory, so maybe I'm a bad example )

There might be some value in local colleges or whatever running little "hey, now that you're an adult, here's how you can use all that math you've mostly forgotten" classes...

1: The uncertainty is I don't remember which year they taught us, not that I can't calculate the answer!! *2: OK, if I think of them as decimal values it makes sense and is semi-obvious. But I'd still just spoon out a bit of the measuring cup.

Re: Why don't we use the math we learn in school?

#123

Post by mulmen »

eternityforest wrote: post #112
mulmen wrote: post #75

Earlier quoted context omitted.

When you say “imperial system” you almost certainly mean US Customary Units. These are not the same system. The United States has never used the Imperial System. Also, US Customary Units have been defined in terms of SI units since 1893. Personally I don’t find multiplying by two any harder than multiplying by 10. https://en.m.wikipedia.org/wiki/United_States_customary_unit... https://en.m.wikipedia.org/wiki/Mendenha…

Multiplying by all numbers is equally easy or hard with calculators, the problem is fractions break UIs. Try adding 3/16 plus 1/2. On a calculator that is three separate operations, and if the output is decimal, you have to convert back to a fraction. And when automated systems convert to fractions, the amount of error is not obvious. With decimals, the computer just adds more digits unless you limit it to a certain…

Nobody is using 128ths of an inch. That’s 7 thou. Realistically anything smaller than a 32nd is going to be in thousandths of an inch and using specialized tooling.

3/16 + 1/2 is 3/16 + 8/16 which is 3+8 or 11/16. That’s simple arithmetic. No calculator needed.

Re: Why don't we use the math we learn in school?

#124

Post by eternityforest »

mulmen wrote: post #123
eternityforest wrote: post #112

Earlier quoted context omitted.

Multiplying by all numbers is equally easy or hard with calculators, the problem is fractions break UIs. Try adding 3/16 plus 1/2. On a calculator that is three separate operations, and if the output is decimal, you have to convert back to a fraction. And when automated systems convert to fractions, the amount of error is not obvious. With decimals, the computer just adds more digits unless you limit it to a certain…

Nobody is using 128ths of an inch. That’s 7 thou. Realistically anything smaller than a 32nd is going to be in thousandths of an inch and using specialized tooling. 3/16 + 1/2 is 3/16 + 8/16 which is 3+8 or 11/16. That’s simple arithmetic. No calculator needed.

No calculator needed assuming you can remember multiple intermediate variables or have the conversions memorized.

It's a great "power user" system for skilled professionals in the pre computer age who practiced with it regularly, and it works well in things like woodworking where you still have a lot of things done on paper or just in someone's head.

It's not the best for CAD first workflows, when you're trying to model everything down to where to clamp the edge guide blocks for the saw, and changing something without changing the model and confirming it will all fit isn't a thing.

In 3D printing you get down to 0.4mm or occasionally even 0.2mm gaps between things, although none of it is really an exact science, and you assume some sanding may be needed to make things fit unless you have an amazing tuned printer.

But I suppose woodworking is less of an issue, because you're probably not going to get even 1/16th precision by hand unless you're really skilled, in which case you probably have fractions memorized.

Re: Why don't we use the math we learn in school?

#125

Post by hickimsedenolan »

dekhn wrote: post #81
technothrasher wrote: post #71

Earlier quoted context omitted.

> What we really need is for every student to realize why math is useful We need to do this for science education as well. The foundation of science that we need the population at large to be educated in is not the steps of the scientific method, how to dissect a pig, or the difference between a covalent and an ionic bond. It is instead logic, critical thinking, rationalism and empiricism, and why science is superior…

it's funny when you mention the difference between covalent and ionic bonds. my teacher in high school chemistry or physics told us cutting a piece of paper was a physical, not a chemical change (the textbook spent a lot of time differentiating those). It wasn't until many years later that I learned that cutting paper breaks hydrogen bonds. H-bonds are neither covalent nor ionic, but more like in-between (partial sha…

Not an expert, but it is a physical chance. H-Bonds are considered as a weak interaction, and making or breaking them (via phase transitions, or in this case breaking H-Bonds) do not change the chemical structure of the compounds or molecules, making them "weak" and "physical," because it is not that hard to do so.

Re: Why don't we use the math we learn in school?

#126

Post by wink »

tharkun__ wrote: post #114
Broken_Hippo wrote: post #45

Earlier quoted context omitted.

Poorly. Many word problems I had were't actually reflective of real world, everyday living. You know, the sort of things folks working a minimum wage job might encounter. I find it absolutely amazing that we haven't done this better since it has been an issue for literally decades.

I doubt even the "real world" ones will make much impression or sense for kids of that age. The farmer Bob example for the fence? Definitely real world. Minimum wage farm hand might not be the one doing the buying of fencing material that's true. 10 year old kid learning that math? Doesn't care one bit about fences, even if you make it "Your family has a dog and you just moved into a new house and there's no fence ..…

To be a little nitpicky about these sort of problem "How many fence posts should Farmer Bob buy"?

"Farmer Bob would be pretty stupid to drive an hour to the hardware store to buy 20 fence posts and 100m of fence, because Murphy's Law and what if one happens to be bad or someone cuts wrong and we're short 2m of fence?"

yes, growing up on construction sites does that to you, the problem is badly phrased if it's saying "should buy" instead of "needs" ;)

Re: Why don't we use the math we learn in school?

#127

Post by hickimsedenolan »

hickimsedenolan wrote: post #125
dekhn wrote: post #81

Earlier quoted context omitted.

it's funny when you mention the difference between covalent and ionic bonds. my teacher in high school chemistry or physics told us cutting a piece of paper was a physical, not a chemical change (the textbook spent a lot of time differentiating those). It wasn't until many years later that I learned that cutting paper breaks hydrogen bonds. H-bonds are neither covalent nor ionic, but more like in-between (partial sha…

Not an expert, but it is a physical chance. H-Bonds are considered as a weak interaction, and making or breaking them (via phase transitions, or in this case breaking H-Bonds) do not change the chemical structure of the compounds or molecules, making them "weak" and "physical," because it is not that hard to do so.

change*, not chance

Re: Why don't we use the math we learn in school?

#128

Post by geoduck14 »

rland wrote: post #8

Math is incredibly useful; probably everyone here knows that. But it's actually fine that most people don't use it. What we really need is for every student to realize why math is useful -- so that if they want to, they can go learn it so that they can make some kind of technological contribution to the world. The fact is, you need to be good at math to make some new fundamental breakthroughs in technology. Those bre…

>Educators say that they're trying to do this, but I'm sorry "how many meters of fence does Farmer Bob need to keep the sheep inside the pen" is not inspiration -- it's drivel

As a counter point, I'm planning on adding drainage to my back yard. I actually am measuring how much pipe I need and how much water I can hope to drain out.

Re: Why don't we use the math we learn in school?

#129

Post by jeffwass »

Once in 5th or 6th grade we had a math homework of a few dozen problems multiplying 3 or 4 digit numbers together.

Totally tedious.

Instead of mindlessly doing it, I spent a few hours making a BASIC program that did the multiplication, but importantly showed all the intermediate steps that we were required to show (eg multiplying by 634 shows the multiplication by 4, 30, and 600 separately).

Writing that program took probably 3x as long, but I wound up learning 50x vs the rote multiplication we were assigned.

Re: Why don't we use the math we learn in school?

#130

Post by geoduck14 »

wink wrote: post #126
tharkun__ wrote: post #114

Earlier quoted context omitted.

I doubt even the "real world" ones will make much impression or sense for kids of that age. The farmer Bob example for the fence? Definitely real world. Minimum wage farm hand might not be the one doing the buying of fencing material that's true. 10 year old kid learning that math? Doesn't care one bit about fences, even if you make it "Your family has a dog and you just moved into a new house and there's no fence ..…

To be a little nitpicky about these sort of problem "How many fence posts should Farmer Bob buy"? "Farmer Bob would be pretty stupid to drive an hour to the hardware store to buy 20 fence posts and 100m of fence, because Murphy's Law and what if one happens to be bad or someone cuts wrong and we're short 2m of fence?" yes, growing up on construction sites does that to you, the problem is badly phrased if it's saying…

>To be a little nitpicky about these sort of problem "How many fence posts should Farmer Bob buy"?

Sure. I'll go with that. Farmer Bob can be a part of a case study. We start off simple.

Farmer Bob buys exactly as many posts as necessary... then he discovers shrinkage/theft/errors

The next project, Farmer Bob uses linear extrapolation from the past 5 projects and buys X% extra posts... but then he discovers new employees break things

The next project Farmer Bob uses Linear Regression, broken down into key variables (like # of new employees)

I think we can get a book deal with this!

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