Monday, March 29, 2010

Humor for History Teachers

Reality Bites, And So Do Customers
Historical Site | Delaware, OH, USA
(I work at a historical site of the civil war, dressing and acting as if we were still in that time period)

Tourist: “Is that fire real?”
Me: “Yes.”
Tourist: “Is the water you’re drinking real?”
Me: “Yes.”
Tourist: “Are your clothes real?”
Me: “Yes.”
Tourist: “Are you real?”
Me: “Yes.”
Tourist: “This place isn’t very interesting.”

Stupid Is Just The Tip Of The Iceberg
Museum | Connecticut, USA
(I work as an artifacts specialist at an exhibit featuring artifacts from the Titanic wreck. We also have a large “iceberg” to show people how cold the water was the night the ship sank.)

Customer: “So is this the actual iceberg that sank the Titanic?”
Me: “No, it’s just a frosted piece of plastic to show how cold the water was.”
Customer: “So where in this place is the actual iceberg that sunk the Titanic?”

Sunday, March 28, 2010

Failing Schools and Turnaround

Go read the editorial: The Turnaround Myth - Failing schools are best shut down at WSJ.

The short version: successful schools stay successful and failing schools continue to fail. Basically the editorial feels that since schools have rarely been able to effect a turnaround (2% success rate) in the past, no one should attempt a turnaround now.

What the writer misses is that closing the school isn't the right answer because it doesn't address the root causes. A champion school will draw in students - good students - because they want to be with similarly good students. A failing school will retain the failures.

Closing a school doesn't suddenly improve the students, it merely forces the picture to reset and the students to move to another school where they will continue to fail. You can rebuild or repurpose the building but if you then fill it with the same problems you had before, you haven't changed or improved the situation. Ignoring this problem doesn't make it go away.

You might get away with redistribution, hiding the failing students by spreading them out among the good schools and letting the laws of averages cover your tracks. The average scores are probably not going to change much if you keep the numbers to manageable levels. The students at hand are still the same but now are placed among better students - is that going to improve them? No. Osmosis doesn't work that way.

Why is Fairfax VA always a top school? Because wealthy people with academically minded kids are willing to move from Michigan to Virginia to get their kids into the high-powered school in a high-income neighborhood. When you separate cream, you have to do something about the skim milk left behind. Fairfax doesn't get that skim milk, they only get the cream.

Throwing away the failing students doesn't improve them, only the school.

Sorry, Arne.

Saturday, March 27, 2010

Basketball, politics and a little Sketchiness

So Arne Duncan (at right, practicing his Oh-so-Superior "White Boy Intellectual Who Knows Better than You" look) is still making noise about the basketball players who don't graduate from college and ruin the US Way of Life because they aren't focused on an education, like he was.

I'm sorry that his dream of "College is an Academic Utopia" and of "Amateur Athletics" is being kicked in the shins, but to pick on basketball is silly. College athletes are not all academically inclined, but they ARE getting the "real-life" training they need to be successful in life. Isn't that the point?

It's time the Education Secretary stopped being so idiotic. These basketball players, at least the "One-and-Done" players, wouldn't be there if the NCAA and NBA and NFL didn't force them to pretend to getting an education.
more below:

Wednesday, March 24, 2010

US Army Officer is Sikh

U.S. Army Capt. Tejdeep Singh Rattan, center wearing turban, stands with other graduates during a U.S. Army officer basic training graduation ceremony at Fort Sam Houston in San Antonio on Monday, March 22, 2010. Capt. Rattan is the first Sikh allowed to complete officer basic training while wearing the traditional turban and full beard since the Army altered the dress code, which had made exceptions for Sikh soldiers, in 1984.

To any who complain about his beard and turban, I say "Wake up." Many of the soldiers standing next to him have been granted equally broad leniency with the old haircut policy - women's hair is allowed to be long under certain restrictions just as his is. The army hasn't come to a screeching halt as a result of allowing women into its ranks and the lifting of the restrictions on Sikhs won't harm it either. I remember when the Army made those changes back in '84 and I can't honestly say I totally disagreed with the decision then, but it kinda nagged at me, you know? At the time, I understood the "clean-shaven" decision to be intended to shape up the force, but the improvements didn't seem linked to the shaving.  It was obviously above my pay grade so I stopped thinking about it, but I am glad it's showing signs of change. (I also think the Navy should allow beards again.)

Times, however, have changed.  The armed forces have morphed into a new form, with radically new and improved tactics, weaponry and manpower.  The addition of soldiers like Capt. Rattan will only strengthen the army.  (And ask the history majors in your faculty about the Sikhs as warriors -- I am glad they want to be on our side.)

So, to Capt Rattan, USArmy: Hoo-ah.

Tuesday, March 23, 2010

Wordy Rubrics and the Search for Higher Thinking

From Jay Matthews comes a tale of an AP teacher who was told by his principal that
“I am not opposed to multiple versions of a test or quiz; it is standard operating procedure for every type of testing program,” the principal said in an e-mail to me. “Instead, I would prefer that teachers use more rigorous assessments when possible, that require written responses and higher levels of thinking. In addition to being more challenging and requiring a sophisticated skill set, these types of assessments are also more difficult for students to copy.”

This has got to be the biggest line of bullshit ever perpetrated on teachers ... that multiple choice is bad and that long answer, essay questions require higher levels of thinking, are more challenging and require a high skill set.


Anyone take the AP math test? How about the SATs and the SAT IIs? How about the Praxis content tests? How about all those college courses? The difficulty and the skill set have more to do with the teacher than the format.

But then, most administrators have never taken actual tests before. They don't understand that I can make a very challenging multiple choice test or an easy one, a challenging calculus essay test or an easy one. I can make questions that take an entire page to answer, that have objective measurement, that take very high skill sets to finish and that bring out the best in my students. Or I can make one that uses a rubric full of things like this from a teacher automatic rubric maker website:

Can someone tell me the difference between a "Good Solid Response with a clear explanation" and a "Complete Response with a detailed explanation" and, while you're at it, perhaps you can explain why being correct is only one of 6 equal parts? Why the intense need for a visual or sketch or for counter-examples? And the "Goes beyond the requirements of the Problem" is a beautiful way of saying that the kid doesn't know beans for what he's doing but he sure is good at typing. Please don't tell me to use a better rubric -- they all seem to suffer from this rot.

Give me the AP scoring method every time. This rubric stuff is utter crap.

Monday, March 22, 2010

Sunday, March 21, 2010

Those pesky nongraduating basketball players

I'm sure you've all read that Arne Duncan wants to prevent schools from joining the NCAA Basketball tournament if they don't graduate enough of their players.

I had a long rant thing going about data selection and narrow-minded politicians, coupled with a healthy dose of "Why hold black players to different standards than black non-players" and "What would you do about the players who don't want to graduate from college. What if they really want to be in the NBA but the NBA won't allow them to join, which has to be discrimination of some kind because white and Asian tennis players and golfers join their professional leagues at 16 and no one says a word."

But I decided that I'd just show these two graphs and ask Arne to explain the obvious problems:

Statewide College Graduation Rates from IPEDS Graduation Rate Survey

Humm, those seem to be aligning with red-state, blue-state demographics, too. Is that the real goal here? Or is Arne just a DUKE / Vermont fan like me? He wants to see all their competition eliminated by fiat instead of by a last-second three? You think Murray State, Northern Iowa and St. Mary's wanted anything less than the best competition, Arne? Get out of the way, Dude. Your mouth and that hole-in-the ground are getting confused again.

Yes, thank you, my bracket is getting CREAMED!
ESPN: 340 points * PCT(%)42.0% * RNK 2,773,415

Monday Morning Update:
ESPN: 380 points * PCT(%)55.4% * RNK 2,132,140

Innovation and Teacher Pay

In my wandering, I came across this little gem on how to fix edumacation:
Instead, a better solution would be:
- Get rid of the unions. Pay for performance, fire the incompetent
- Give teachers the independence to try new things and tailor to individual classrooms. Reward success.
The list continued but I particularly liked the juxtaposition of "pay for performance, fire the incompetent" and "Give teachers the independence to try new things. Reward success." Beyond the obvious (to me, at least) problem of determining teacher competence, how much do you suppose a teacher will innovate and try new things if his paycheck is based on performance, with firing being a instant option for a moronic administrator if that new idea fails?

In all of the pay-for-performance schools I have studied, the one constant factor is that the teachers all retreat into "safe" zones of teaching. Most teachers would rather be assured of a job, thus follow the demands of the administration, teach to the test and be nothing special, rather than go out on a limb and risk it all on a double or nothing bet. The feeling seems to be that it is better to be good than take a wild and unproven chance with your students' education, risking your job. It's sad, really.

There is usually a maverick who bucks this trend but he merely proves the rule - he is unmarried or for some reason doesn't need to be employed at that school. Perhaps he's a certified TIG welder or has an engineering degree with experience.

Unions and union rules allow teachers to innovate, try new things and then adjust them to work better next time. You get "The Creative Feedback Loop Of Teaching"(Thanks to Dan Meyer for the expression, in this post, near the end.), but only if you have the freedom to innovate and aren't locked into a scripted curriculum or stuck in a repressive, vindictive or moronic administrative system.

True innovation comes from those who can afford to try. Trying implies failing occasionally. If you punish failure, you stifle innovation.

History Channel? Not so much.

History Channel is losing it's way, I think. I receive the prime-time schedule in my email every week and it's becoming more and more obvious that they are following the news down the rabbit hole of non-reality and sensationalism.

I remember the news. It had an anchor and the anchor presented the news. Topic by topic. No teasers, no games, no silliness until maybe at the very end. Now, you get three minutes of scandal, a teaser for sports ("local boy did something amazing today"), another teaser for the weather (smiling way too much - "Weather is gonna SUCK!"), then commercials. Repeat. It seems there are more minutes devoted to the teasers than to the stories. All this because some pollster said that people WANTED that.

History channel used to be about history. Agreed, it seemed to have lost the keys to all of the film cabinets except WWII, but at least it was history. Now, we have "customer-driven", "popular-interest" shows like Ax-Men and IceRoad Truckers. In these days of specialty channels, one would think the History Channel could stick to history, but I guess not.

As the schedule below indicates, they don't do any real history until Friday night - gangs existed in the past but not on this show. Saturday night is finally history - sex in history - but then we're back to the joke shows Sunday night.

"Apocalypse Island - Does a remote island in the middle of the Pacific Ocean hold the final clue to the Mayan's apocalyptic predictions concerning 2012? One explorer thinks he's discovered the answers that have eluded man for centuries." "Um, What is stupid TV devoted to the low-grade imaginations of conspiracy theorists and UFOlogists? Alex?" Correct, for $1200. Not that this show actually tells you any of these answers or actually has something definitive ... they just asked you a question. Does a remote island hold the final clue? Um, no. Apparently not.

Bleah. I've gotta get back to work.

Saturday, March 20, 2010

Credit Scores and Correlations, with a little Politics

Yahoo News has a story about loans and credit scores. It starts with the typical hook of misstating the case and then appeal to pity:
WASHINGTON (AP) -- Some homeowners who sign up for the government's mortgage assistance program are getting a nasty surprise: Lower credit scores. For borrowers who are making their payments on time but are on the verge of default, the Obama administration's loan modification program can reduce their credit score as much as 100 points. That makes it harder to get a loan and can present a problem when applying for a new job. Housing counselors say it's unfair, especially because the news often comes as a surprise to homeowners.
Doesn't anyone notice that the whole idea of credit score is Character, Capital, Capacity? If you need the credit modification, you are implying that you are having trouble paying off your current obligations. If so, why would you expect that your credit score wouldn't reflect that? If your capacity isn't up to your current loans, why is anyone surprised that the credit rating drops to reflect that and make it harder for you to borrow even more?

Here's the "correlation does not imply causation" part:
"Why should people's credit be hurt even worse when they're trying to do the right thing?" said Eileen Anderson,

And many homeowners are angry that a program designed to help carries such a penalty, said Kathy Conley. "It's a feeling of being duped,"
Interesting how the President's program is blamed for the drop, not the credit agencies who change the score or the homeowner whose financial situation does not warrant a high credit rating.

Dude wanted a car.
"[he] had to apply for the loan. He was shocked to learn that, after signing up for the Obama plan, he was denied. "I should have been told," that this might happen, Owens said. "Without credit, you can't do a whole lot in life."
Dude is a moron.

Thursday, March 18, 2010

Books, Part Deux

Yesterday, I mentioned the books that I have, Part One. Those were the easy-to-read books. I got class sets of those.

The books below are harder to read, with a more limited audience so I only got 3 or 6 of each of them. They are the books a serious math student should have read, so I encourage them to try.

The "Biographies"
These biographies are written for the serious and capable 12th grade student or college student. The writing is very clear and the topic is fascinating for me. My students, not so much. An Imaginary Tale; The Story of i. A funny thing about this one was when I tried to type up the order to present it to the decider-person -- I couldn't type "i" without Word getting all angry at me.
e: The Story of a Number. Maior is a good writer, but not for the faint of brain. Also, try Zero; A Biography of a Dangerous Idea and The The Golden Ratio: The Story of PHI, the World's Most Astonishing Number .

Of course, there's John Allen Poulos:
A Mathematician Reads the Newspaper, as well as Mathematician Plays the Stockmarket and the inservice classics: Innumeracy and Beyond Innumeracy. He has some others. Try them if these do good things for you.

Damn Near Impossible for High School Students. (If that's not a challenge, I don't know what is ...)
A Brief History of Time by Hawking. You gotta throw down the gauntlet.

Tuesday, March 16, 2010

Math Quiz for Presidential Candidates

Darren writes that the President has become innumerate. This immediately brought to mind Paulos's proposed "Math Quiz for Presidential Candidates."

I agree completely. I think students should know most of these, too, so I gave the quiz to some of my classes when I was sick. I told the sub to try it as well, but she refused!

I think 6 is my favorite. (Below the fold)

Books on the Shelf.

What's in my classroom? Well, I like books and there was money in the budget, so ... someone had to do it. I ordered with this philosophy: if the book was an easy read, I tried to get a class set which could be lent around the department. If not, I got maybe 3 or 6 which I could lend to individual students.

Here are a couple of the easy reads:

Short Circuits.
One-Minute Mysteries: These are really easy but a good way to while away a few minutes of TA or homeroom. They are one- or two-paragraph mini-mysteries in which the criminal makes one mistake or one misstatement that shows his guilt. "How could he have known the victim was killed with a potato peeler if he wasn't there?" A similar book is Two Minute Mysteries, which is more of those "outside the box thinking" or "lateral thinking" puzzles. These can take a while because the kids have to come up with reasons that aren't readily seen or intuited. Some reasons fall into the category of "WTF? How are we supposed to know that?"

Huff's How to Lie with Statistics is a classic. I use at least some of the ideas in every class from consumer math through Pre-calculus. I also make the speech before the students start their science fair projects. See also "How to Lie with Maps."

From the guys who brought you Klutz's Guide to Juggling comes Cartoon Guide to Statistics. It's great. In fact, when I unpacked the books, the other math teacher instantly borrowed it. Gotta be a good sign! Witty and fun, it's still got the STUFF. The cartoons are quite descriptive and the math is all there, even if the 'toon of Galileo is goofy.

If you haven't read it ... Freakonomics (and the sequel, Super Freakonomics) is a really good collection of statistical stories and case studies. Leavitt is a good writer and he analyses his work in engaging and easy-to-read chapters. "Why Do Drug Dealers Live with Their Mothers?" and "Why is the KuKluxKlan Like a Group of Real-Estate Agents?" You'll want an entire Saturday for it.

The Number Devil is a good book for starting kids reading about math topics without slapping them silly. Easy to read but not pandering either. Probably the best explanation for the Fibonacci sequence I've seen.

Loosely organized book of trivia and generally "neat stuff" is Brain Fuel. Engaging reads of one or two pages each that aren't particularly mathematical but I was able to buy them, so there! Kind of "Ripley Believe it or Not".

If it's a math class, it has to have Flatland & Sphereland in it. Misogynistic? Yes. Satire? Yes. Still, it's an exploration of geometry you shouldn't be without. Available online for free (long out of copyright), but you'll want tangible books. Fortunately, they're cheap.

SAT Prep
For my SAT Review class, I was able to score some $3 versions of Prince by Machiavelli and Sun Tzu's Art of War. These are used as essay topics. I'll take a paragraph almost at random (they're that good for this kind of thing) and make a question about it. Instant Essay topics.

For the same course, I got - and this is no shit - a copy of Specerian Penmanship. The students are fascinated by my ability to write cursive. Probably 50% can write poorly in cursive, the other half not at all. I, of course, had Mrs. R. to teach me this some 50ish years ago. So I lend out the workbooks with the stern instruction to use a piece of paper placed over top. SO far, no writing in the books. A couple girls have really worked on it. So funny. One texted this fact to her friend - proud she was teaching herself to write cursive. The irony escaped her.

Drafting is important.
How to Read/make Mechanical Drawings and Popular Science's The Art of Mechanical Drawing are good source books for orthographic projections and for general work. I feel it very important that students learn the basics of drafting. The art department is getting swamped and stamped and cut these days and the technical centers are becoming more exclusively for "tech kids" - where's the generally good student to learn this stuff? ME!

I can't say anything yet about 100 essential things because it's backordered.

That's a part. I'll talk about some of the rest tomorrow: the tough reads, the ones that I bought only 3 or 6 copies of.

caio for now.

Sunday, March 14, 2010

Happy PI Day

Can't help it:

Death of a Calculator.

Time to play "The Last Post" and "Flowers of the Forest" for the venerable TI.

Schools have been buying TI-84s for their students for years now. TI-83s before that, or 85s or 82s. I believe that the game has fundamentally changed.

The iPhone app store has a graphing calculator app for $0.99. It's not perfect ... yet.

The comments from buyers ask for intercepts, regressions and a few other things but the days of 92 x 68 dull gray pixels is close to over.

I say "Good Riddance."

For far too long, TI has coasted on its laurels, allowing a once-perfect idea to gradually fade into a crappy has-been of technology. The TI is slow, expensive, big, cumbersome and limited to the buttons at hand, though the Non-Inspiring Inspire does allow you to change the faceplate. The screen resolution is the same as was available in 1990 with the TI-82, for crissake. Twenty years and practically nothing new!

I was wondering when someone would produce an app for the handheld device many of them carry already. It has color, better interface, finer resolution, quicker graphics, you name it.

No school should bother purchasing more TIs. Let your current ones be augmented by those kids who have a smartphone and the ITs will break or kludge down at about the same rate as your students proportionally get smartphones.

Look at these screenshots from the AppStore. So far, and I stress that this is only temporary, the TI competes with this thing. The TI has too many nifty things built in for this guy to compete with. But! How long will it take for him or someone like him to mimic every useful TI function? Not too long.

The kids need to develop an understanding of cellphone etiquette, fair use, proper use -- something that schools are just going to have to deal with. We can't put this off. This issue will be front-burner next year (2010-2011, for anyone reading this in the archives) if not for exams this year.

That'll be another post.

Saturday, March 13, 2010

Idiocy in Denver

SO the State of Colorado wants to tax and the anti-taxers are screaming.
"... a recent study on "Amazon laws" concluded online companies would have to deal with more than 8,000 different tax computations should every state join Colorado's effort. Amazon would be nuts not to fight."

Oh, please.

What really needs to happen is a federal law that states that online merchants need to collect tax based on the destination of the package rather than on the location of the sender's warehouse.

Argue about paying taxes. I get that. Argue that taxing the local warehouse will induce Amazon to move the warehouse to a tax-free state. I get that, too. But if you argue that Amazon couldn't figure out how to do it, you're talking out the wrong end of your body. It's just silly.

Amazon is entirely run by computers. Orders are taken over the web without a single human intervening. The warehouse is run by computers that tell every worker exactly what to put in what size box and then slap a label on it. They figure out the shipping details for millions of people, millions of destinations, and millions of shipments a year. They send out email tracking details, feedback emails, follow-up emails, and a host of other automated stuff.

There are at least a dozen shipping options and at least six payment options. Each person has one (or many) different address options. Amazon must deal automatically with customs to every one of the 200-odd countries they ship to, monetary conversions for all those, multiple websites (one for each major country). You purchase details are kept meticulously and all of those records are used to build recommendations and to track your online movement.

They must deal with thousands of publishers and suppliers, each with different options, deals, and profit percentages. They have thousands of "Used and New" resellers, with all of their charges and costs, all getting 60% to 85% of their money (the rest is Amazon's cut) - and those deals change all the time.

And you're trying to claim that they can't figure out how to charge me 6% tax and send it to Vermont?

I'm actually required to pay taxes on all purchases that I bring into Vermont from tax-free locations - the snowblower I buy in NH, etc. There's a place for it on my tax form. (Or car registration - they charge the 6% to register it.) If I go to a gunshow or any convention and buy something, it doesn't matter where I live or where the vendor lives, I have to pay local sales tax. Is that destroying civilization? No. Somehow the guy manages to get a local vendor's license and tax number.

I don't like taxes and I love tax-free Amazon. I would love to do without taxes.

Just don't claim that Amazon is somehow incapable of a simple** programming task.

** Simple compared to what they do for everything else.

Article below, if it gets deleted or archived.

Monday, March 8, 2010

Sunday, March 7, 2010

Schedules from Around and About

Mrs. H asked and we happened to have this information available and here is much easier to format than the silly little comment window. Some information is not available and few schedules include a lunch because all of the schools have an extra long period during which a 20-minute to 30-minute lunch is extracted. Simplicity dictated we not mention lunch. If this is helpful to anyone, have at it.

This is mostly boring and is hidden below the jump:

Google expands its reach

Sometimes Google needs to just chill. Other times, they are on the right track. This is one of the good times, I think.

Streetview now goes underwater.
Satellite mapping now includes aerial pictures from World War II and forward.
(sorry, jd. I should have mentioned: Google Earth.)

This is seriously cool. They got permission to include War Department images and they've put them in the correct places on the current-day maps - overlay form. Seriously. Visit Dresden, Germany and look in the corner of the screen for a "History" slider. If there's available images in your current view, you can set the date back to any time for which they have a picture.

Update, Screenshot:
I've gone to Dresden and clicked the little clock icon to show the historical slider. The little blue lines in the slider indicate what's available and I've chosen Dec 1943. The vague green area outside the city is off the image.You can then slide back to the present and compare the rebuilt city with the old image.

Isn't that awesome?
GOOGLE Earth mapping service is letting people use the Internet to dive into the world's oceans or see the ruin that World War II bombings rained on European cities. The Internet powerhouse on Thursday added an Ocean Showcase and WW II era aerial photographs to its free, interactive on-line atlas.
"The historical imagery feature gives people a unique perspective on the events of the past using today's latest mapping technology," Laura Scott of Google Europe said in a blog post. "We hope that this World War II imagery will enable all of us to understand our shared history in a new way and to learn more about the impact of the war on the development of our cities."
The feature includes images taken in 1943 of 35 European cities pictures and of war-battered Warsaw in 1935 and 1945. Google Earth users are able to do side-by-side comparisons of the cities then and now.

Olympic Rates

What Can You Do With This?
A couple of things struck me ...
  1. Is the video still at when I want to use this again? - nope.  Yes!
  2. How fast are they going?
  3. If two racers were both on the same course at the same time, how much distance would separate two racers at the finish ? (already in the table)
  4. What is the angle of the slope?
  5. Results are here - how long they'll stay?
What else?

With thanks to Dan Meyer for the Theme.

The Highly Ineffective Principal is Usurped.

There are so many things wrong here, I just don't know what to say. Hold on, I DO know what to say. I think these folk have usurped the title of Most Highly Ineffective Principal. If you can't teach 'em, suspend 'em!
  • School Officials: Grow Up. If this is the extent of his "intimidation," then you need to seriously reconsider your actions. If he made other students uncomfortable, then you need to talk to him and to them and help everyone understand the meaning of "Play" and appropriate things. If this is too complicated for you adults, then you should quit your position and get a job you can handle. Like maybe at Burger King.
  • Momma: Grow Up. You're the Adult. Teach your son how to behave. If they've complained about this behavior for several months and you've ignored it, then you have also failed as a parent. You have to realize the school is unwilling to do (or incapable of doing) this. Teach him proper behavior. Nobody cares if your son isn't violent at home - we all know what a special little snowflake he is, unique and wonderful.
Say it with me again, "Zero Tolerance means Zero Intelligence."

Ionia kindergartner suspended for making gun with hand
By Brian McVicar The Grand Rapids Press
March 04, 2010, 10:39PM
IONIA -- To the little boy's mother, it was just a 6-year-old boy playing around.
But when Mason Jammer, a kindergarten student at Jefferson Elementary in Ionia, curled his fist into the shape of a gun Wednesday and pointed it at another student, school officials said it was no laughing matter. They suspended Mason until Friday, saying the behavior made other students uncomfortable, said Erin Jammer, Mason's mother. School officials allege Mason had displayed this kind of behavior for several months, despite numerous warnings. "I do think it's too harsh for a six-year-old," said Jammer, who was previously warned that if Mason continued the practice he would be suspended. "He's six and he just likes to play." Jammer says her son isn't violent, and there are other, more effective ways of teaching him not to make a gun with his hand. "Maybe what you could do is take his recess away," suggested Jammer, adding her son doesn't have toy guns at home. "He's only six and he doesn't understand any of this."

Saturday, March 6, 2010

More on Monty Hall

Ah yes, the famous Monty Hall Problem.
Suppose you're on a game show, and you're given the choice of three doors. Behind one door is a car, behind the others, goats. You pick a door, say number 3, and the host, who knows what's behind the doors, opens another door, say number 1, which has a goat. He says to you, "Do you want to pick door number 2?" Is it to your advantage to switch your choice of doors?
First, we have to get beyond the farm kids who say that they wouldn't mind having a goat because a Cadillac wouldn't make it up their driveway anyhow, the kids who think this is a stupid idea for a show and the kids who are sulking in their hoods because this so BORING. Occasionally, I'll  change it so the loser doors have a pinata filled with used cat litter - which is often funnier.

"It's fifty-fifty because there's only two doors."

"Lucy, I've got some 'splainin to do."

The statement of the problem is crucial for the students to understand why the problem isn't simple probability, choosing between two doors randomly.

It's because Monty didn't choose randomly that you don't. Monty KNOWS where the prize is. This changes things from "Monty chooses one of two doors randomly" which would make yours a 50-50 choice as well. Instead, it's "Monty's knows" and avoids the real door which messes up the probabilities.  Realize that Monty never, in all those years and all those shows, ever opened a door and said "Ooops, there's a car, you lose."

Like for all of you, that never helps with my students either so I try the twenty doors version next. Choose door 1. Monty opens all the doors except number 13. Stay or switch to #13?

Everyone wants to switch. But no one will accept the same reasoning will hold for the 3-door version. "Because we are dealing with only two closed doors. DUH." "It's still 50-50, Curmudgeon."

So I ask the students for a brute force solution. How many different possibilities are there? What are the results? It comes quickly to this:

Here are all the possibilities:

1 1 2/3 10
1 2 3 01
1 3 2 0 1
2 1 3 0 1
2 2 1/3 1 0
2 3 1 0 1
3 1 2 0 1
3 2 1 0 1
3 3 1/2 1 0

Pretty plain. Switch wins 2/3 of the time.