## Tuesday, May 28, 2013

### I hate it when smart people are wrong in public.

Ordinarily, this guy is correct, but this time he screws up:

"If you went to elementary school in the US, you almost certainly learned about the order of operations."

No, you didn't.

What he should have said was, "If your elementary school teacher was incompetent in math, she taught you this."Which is why we need to seriously rethink the training of teachers in this country.

"If you went to elementary school in the United States (or much of the rest of the world), you almost certainly learned about something boringly called the "order of operations"- a set of rules for whether or not you should do multiplication before addition or addition before subtraction to get the right answer on your math test.
Except, you don't always get the right answer, or even, one answer - I mean, is 8-2+1 equal to 5 or 7? and is 6/3/3 equal to two thirds or six? - the problem is, focusing on the order of operations can lead to ambiguity and obscures the real, underlying, and often beautiful mathematics."

FAIL.

## Monday, May 27, 2013

### Folk remedies are SOOOO much better than vaccines.

Said no doctor, ever.

It just boggles my mind that people still believe Andrew Wakefield's bullshit.

## Saturday, May 18, 2013

### Practicing my speech. "When will I ever use this?"

Originally posted on 3 April 2010, but I wanted to say it again.

"When are We EVER going to have to use this?"

"Beats me," I usually answer. "You can't even tell me definitively what you'll be doing next month, forget about four years from now. How can I definitively say when or whether you'll use THIS?

All I can say is that it is useful in certain situations (the word problems in this section are limited versions of the same problems some people face daily), useful as mathematical development for later work (which may be a prerequisite for the course or job you really wanted) or as mental development to expand your brain beyond the limited understanding and very limited world-view you currently have. I'm not being critical here - you really have no experience at life. How could you possibly know the utility of everything you're learning?"

You have millions of possibilities ahead of you, thousands of doors along this hallway you call life.

Writing ability will unlock many of them, artistic ability others, mathematical ability many more. Some may require that you speak English well - certainly 95% of the jobs in this country do. Some will require a little of everything.

Each of these doors is along a different stretch of hallway. Each educational decision you make takes you down one branch or another, closing off some possibilities and making others available. To switch from one branch of the tree to another may require a little backtracking to pick up things that you could be learning now.

I have no idea which doors will interest you so I have to lay a very broad groundwork and push you in directions you may not immediately see any need for. You have to trust that, over the course of many years and many students, I have a good sense of what you might need and of what you may find interesting after we're done.

How do I know this? I talk to my students after they graduate. They tell me what they found useful or pointless. I get all kinds of stories about topics that we covered here that directly applied to something they were working on, stories about being the only one who really understood something the professor was trying to say. There aren't many complaints that we spent too much time on a topic they never saw again.

If there is ever a commonality in the comments of returning graduates, it's this: 'I never imagined that THAT would be useful. I was surprised when it showed up. So was the professor - he was grateful SOMEONE knew about it.'

As Seth Godin mentioned the other day, the odds of becoming anything in particular are pretty slim. The odds of being able to land that gig at the radio station are pretty small, considering that the current jobbers probably want to keep their jobs. The odds of being a pro basketball player are less than 1:1,000,000; of becoming a developer for the software firm down the street or the next Andy Warhol, virtually nil."
The ardent or insane pursuit of a particular goal is a good idea if the steps you take along the way also prep you for other outcomes, each almost as good (or better). - Seth Godin
You can't pick a single destination because that destination might not be there when you arrive. Choose instead an education that can branch unexpectedly to fit the sudden turns you'll face.

What courses should you take? Everything you can. This is the last time education is free. Take drafting, poetry, physics, sculpture, statistics, history, psychology, another language. If you can take it, you should take it. If you find out you hate it, then no harm done.

Did you know that the Spanish teacher can also teach Russian? No, I don't honestly know how you, personally, will use Russian, my little snowflake.

I don't know how you'll use a knowledge of parabolas or an understanding of rates of change, either. I know how I use them and how my friends use them, but I can't speak for you. I can watch anime in the original Japanese and catch a smattering of the dialog. Is that reason enough to take Japanese? It wasn't the reason at the time I took Japanese but it is neat now. My Japanese students still laugh at my speaking ability (or lack thereof).

I won't bother to tell you that I used parabolas to design an archway in the garden because you don't care. I won't tell you how a recent graduate earned \$30 an hour in her first collegiate summer helping her professor build a radically new type of solar panel - because you'll just say that you're not going to study that. Neither does she, but her knowledge of calculus, biology and chemistry is why she got the job. I won't tell you how an actuary uses probability and statistics and calculus to predict random events.

Here's a fundamental truth: If you don't learn it now, you will never be able to use it and that will be a huge disappointment for you.

Let's try a thought experiment to see another reason why I reject your casual dismissal of this course. Try these statements on for size:

(A) You're black and I won't let blacks take the difficult math classes because it's too hard for them; their brains aren't developed enough.
(B) You're a girl and everyone knows that girls can't do math. You should change to elementary education.

Angry yet?

It's wrong, isn't it?

If I were to say that I was not going to allow you to take this math class because you are Hispanic, or Black, or female, you would be all over my case for discrimination. You are capable enough and you should be allowed to take whatever you want ... so why do you willingly do to yourself what only a blatantly racist and sexist asshole would do to you?

To sum up: I don't know when, or even if, you'll ever use this. Please don't let your current malaise lead you to ignore this work and prevent you from doing something you are fascinated by in the future.

Remember that hallway? Don't slam those doors in your face before you even get there to see through the peephole.

See you in math next year, kiddo - maybe even AP Calculus.

From SMBC

## Wednesday, May 15, 2013

### Rational or Irrational Numbers

How does the title of the example "Using Irrational Numbers" jibe with the question "To the nearest ten meters, how much farther is ..."?

I get that this is a pre-algebra textbook, but it seems to me that a discussion of irrational numbers should deal with irrational numbers, or at least with answers rounded to the nearest hundredth or something.

Maybe the start of a discussion of significant figures and tolerance and error?

## Monday, May 6, 2013

### How many more to get 99%

What's the deal?
How many are needed to hit 99% ?