# One is not prime

Discussion in 'Community Discussion' started by Doctor Q, Jul 13, 2006.

### Staff Member

Joined:
Sep 19, 2002
Location:
Los Angeles
#1
It bothers me when students are taught "facts" that are just plain wrong. It's hard enough deciding what kids should be taught about controversial subjects in classes about history, social studies, culture, etc., but I think it's inexcusable for them to be mistaught facts that should be common knowledge.

Being a school volunteer, I've often heard lessons in progress and have repeatedly noticed these mistakes. Sometimes it's carelessness by teachers. Sometimes teachers don't know the facts themselves. And sometimes there are mistakes in schoolbooks.

Here is one exampe of each case, from my personal experiences:

1. An elementary school teacher had students copy a list of spelling words off the whiteboard. The teacher had misspelt one of them on the board, and all the kids copied it down that way, took it home, and studied it for a week. I didn't learn what happened when they took their test the next week, but I wonder if they managed to "unlearn" it later. This particular teacher did this more than once.

2. Another elementary school teacher taught the class that 0 divided by 0 is 0. When I heard about it from a student, I talked to her about it. She told me she is right, that 0/0 is always 0. I tried to correct her, saying that 0/0 is undefined, or at least indeterminate (you can make cases for 0/0 having various values using various mathematical approaches), but she simply didn't believe me. I also couldn't talk her into not mentioning 0/0 at all. She continued to teach it that way.

3. This week, I helped a class of middle school math students, and discovered that their school-issue workbooks gave them a list of prime numbers to factor, including the number 1. Primes are "positive integers that have exactly two factors" and 1 does not have exactly two factors, so 1 is not prime. This isn't controversial; it's just a definition. Yet these students will learn that 1 is prime from their books. I alerted the teacher, who agreed with me and will explain the mistake to the students.

I don't intend this thread to be about math; that just happens to be the type of mistake I'm most likely to notice. My point is that it's a shame when students are taught the wrong information about basics like spelling and math, and I find it disappointing.

Have you, as students, teachers, parents, or other observers seen the same thing? How often does it happen?

2. ### Applespider macrumors G4

Joined:
Jan 20, 2004
Location:
looking through rose-tinted spectacles...
#2
They'll get a shock when they use Excel and get a #DIV/0 message...

### Staff Member

Joined:
Jan 20, 2005
#3
Ah yes, my fiancée still loves to tell her Trivial Pursuit prime number story. One night in college, they were playing one of the earlier editions of Trivial Pursuit (I don't remember which genus), and she got the question, "What is the third smallest prime number?" She correctly answered "five," but Trivial Pursuit gave the answer as "three."

So she pulled out a piece of notebook paper and wrote a drunken longhand letter to Trivial Pursuit explaining that one was not a prime number and how several important mathematical concepts collapse if it is allowed to prime. Several weeks later she got a letter from Trivial Pursuit thanking her for contacting them and explaining that "many, many" people had done the same. But since the edition was not going to be reprinted, there was nothing they could do to address the issue.

4. ### ham_man macrumors 68020

Joined:
Jan 21, 2005
#4
Question from my 8th grade US History test...

"Which one of these future presidents was a leader during the Battle of New Orleans?"

B. Andrew Johnson
C. Abraham Lincoln
D. John Polk

"Ummm...shouldn't B be 'Andrew Jackson'...?"

"No"

"No, you're wrong."

"I'll be right back."

At that moment I went and looked up Andrew Johnson's birthday in the dictionary...

"OK...see here...Andrew Johnson was born in 1808. That would make him just under 6 years old when the Battle of New Orleans occurred."

"I don't believe you. Are you ly-"

"Awww...screw it..."

...and that was that...

5. ### mactastic macrumors 68040

Joined:
Apr 24, 2003
Location:
Colly-fornia
#5
So when was the War of 1812? And just who is buried in Grant's Tomb?

My father, who teaches history, has had kids get these "gimme" questions wrong on tests before...

6. ### Queso macrumors G4

Joined:
Mar 4, 2006
#6
I can imagine it. Lots of "Bloody Microsoft!!" type swearing

7. ### monke macrumors 65816

Joined:
May 30, 2005
#7
I've seen it happen.

One time I was at a hockey game, when a lady walked up to me and said "Excuse me, can you tell me when the ref is going to blow the whistle, I need to go to the washroom"

Does the cruise leave the boat?
Do they drag a power line behind the boat for electricity?

8. ### Tanglewood macrumors 6502a

Joined:
Jun 7, 2006
Location:
San Diego, CA
#8
There are ignorant people everywhere, its our job to enlighten them.

or just talk about them here

9. ### mactastic macrumors 68040

Joined:
Apr 24, 2003
Location:
Colly-fornia
#9
My favorite was being near a clueless person at a Sharks game who wanted to know when halftime was.

10. ### iSaint macrumors 603

Joined:
May 26, 2004
Location:
South Mississippi y'all, near the water!
#10
All the time! Those who will succeed beyond what is being incorrectly taught in schools are those who have supportive and involved parents.

11. ### Tanglewood macrumors 6502a

Joined:
Jun 7, 2006
Location:
San Diego, CA
#11
Hell, half the maps found at the back of the history books when I was in K-12 still had the USSR, Serbia, Czechoslavakia, etc...

12. ### Leareth macrumors 68000

Joined:
Nov 11, 2004
Location:
Vancouver
#12
My favorite was from high school : matter takes up space and has mass but energy has no mass and takes up no space , thats the difference between matter and energy
then I get to university, energy becomes a property of matter... and it does have however minute mass... arghh! I guess E=mc2 looks good as wall decoration when one does not think about it.

Another one is one prof insisting that ther eis no such thing as anti-matter...

and another physics prof talking about centrifugal force as if it was a real force... hmmm they all came out physics issues...funny since physics was only my minor...

Oh one more : the feminist instructors at my uni using the term "herstory" because "history" is too male...umm our school has a really great linguistics depts I suggest they go there and talk to the people on the origins of the word "history" is comes from the GreeK " historia" which I might add is a feminine word...or the stupid spelling 'womyn'...arghh these words should not be used in academia...

13. ### UKnjb macrumors 6502a

Joined:
May 23, 2005
Location:
London, UK
#13
As a bio-medical research scientist, I have a constant battle with the difference between correct and incorrect "facts". I love maths and numbers and like to think that I am relatively numerate; I have just learned here that my working definition (a number is prime if it is only divisible by 1 or itself) of a prime number is wrong! Although a quick Google search (prime number definition) indicates that there is a degree of controversy around the subject.

Knowledge of any one fact is very expensive by any definition, but especially one that involves the intellect. The more I understand in pedantic detail about my own chosen area of interest, the more I realise how completely ignorant I am of it. Except I know so much! Enough to teach undergraduates, graduates and medical research fellows. And their ignorance can be so impressively profound. Obviously they have a working knowledge of their basic subject, but challenged within my own specialist area, they remain ignorant; that's why I am the teacher. A real dilemma. Maybe there is a balance between knowing the basic principles of a subject and the detail that only specialists can get bogged down in. So I am not sure that individual examples like "One is not prime" is really helpful. Maybe I miss the point. It seems to me an esoteric example of how the fine detail of a principle may be wrong, but a commonly-held view of what constitutes a prime number is still correct in broad practice.

For instance, depending on the level of education/understanding/whatever, it is entirely correct to make the assertion that time does not exist. Counter-intuitive, appearing totally wrong and difficult to argue. But it remains an acceptable viable assertion, although not based in fact, just (very solid) theory. So if I hear a teacher say that time is measured in blah blah blah, do I jump in and point out that he/she is wrong? Don't think so.

Again, and this is fact, glass is not a solid - it is a super-cooled liquid. Is anyone to criticise the fact that the general population does not know this and thinks that glass is a solid? On a workaday basis, of course glass is solid.

I do agree that it is disturbing that formal educators can seemingly get it so wrong on the obvious - like arithmetic results *2 + 2 = 5* - but go deeper into the higher levels of any subject and there seems to me a bit of a problem because ---- one man's understanding is another's ignorance. And it becomes very very expensive to sort out the truth of the matter.

To lighten up a bit, I was teaching a bunch of med students about the vascular system and pretty much asked a rhetorical question "how many chambers does the human heart have". One guy stuck his hand up and replied "Three"! I still don't know if he was taking the pi\$\$ or was genuinely ignorant.

14. ### EricNau Moderator emeritus

Joined:
Apr 27, 2005
Location:
San Francisco, CA
#14
In elementary school, when learning cursive, the teachers say, "You'll need this for the rest of your lives." ...I haven't used it since 6th grade... and I never will.

Joined:
Dec 19, 2002
Location:
NYC
16. ### Applespider macrumors G4

Joined:
Jan 20, 2004
Location:
looking through rose-tinted spectacles...
#16
Possibly just had his heart broken?

17. ### ejb190 macrumors 65816

#17
Don't even get me started about flawed logic in science text books. If you want to make a case of it, even the "scientific method" is flawed.

18. ### Jesus macrumors 6502

#18

[Etymology Nazi]Historia is a latin word.[/Etymology Nazi]

### Staff Member

Joined:
Jan 20, 2005
#19
Um...if it was or, every number would satisfy that description.

20. ### XNine macrumors 68040

Joined:
Apr 7, 2005
Location:
Why are you wearing that stupid man suit?
#20
In High School I had a US History teacher that set up an assignment. I was out the first day everyone picked groups of two, so I was the only person in my group when I came back.. Basically, the assignment was that we had so much money to build a railroad that stopped in 2 places in each state that went from coast to coast. The teacher would then start natural disasters or wars or whatever to raise the price, and we had to accomodate all of this, complete the railroad, and not go bankrupt. But whoever came out with the most money, won.

Well, this group next to me built the opposite direction from what I did, and so, in order to win (and get 3 days of no homework) I told the group I would sell my railroad (which matched there's exactly coming from the other way) for 2 million dollars. They agreed.

I beat everyone by AT LEAST 1.2 million dollars. So I won, right? Yeah, she didn't like it, so even though she said I won, she didn't acknowledge what I had done and instead gave me homework the next three nights. effing whore.

21. ### EricNau Moderator emeritus

Joined:
Apr 27, 2005
Location:
San Francisco, CA
#21
...which came from Greek.

History:
ORIGIN late Middle English (also as a verb): via Latin from Greek historia finding out, narrative, history, from hist?r learned, wise man, from an Indo-European root shared by wit 2 .​

22. ### yg17 macrumors G5

Joined:
Aug 1, 2004
Location:
St. Louis, MO
#22
I had to take an intro to web design course last semester. This is at University of Missouri-Rolla, which for those of you don't know, is an excellent school for engineering and technology in general. Just a slight step behind schools like MIT. You'd expect there to be good instructors. Anyways, it was obvious my teacher had no idea what the hell she was talking about. A majority of the class was crap like guidlines for designing pages, not actual HTML, but we dealt with Dreamweaver a bit. Then, when she (tried) to teach actual HTML coding one lecture, it was a bastardized version of HTML4 she taught. No XHTML, which makes most sense to me. She taught things like <br> instead of <br />, alt tags on images were optional, she completely ignored the doctype declaration. Then she taught that /* this style of comments */ were acceptable to use in Dreamweaver's code view, but not notepad or other text editors, as if DW would convert them to <!--comments-->. Imagine her shock when students tried /* */ and it didn't work! She was possibly the worst instructor I've had there (unless you count the 2 that spoke no English whatsoever). And I found out that I have her again next semester for the "advanced web development" class. This is stuff like PHP (or at least some web programming language, but I think PHP, which is good, since I know PHP very well), interaction with said programming language and databases, web server administration, stuff like that. Should be interesting to see what she f*cks up this time.

### Staff Member

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Jan 20, 2005
#23
According to the built-in OS X dictionary, it's originally from Greek.

24. ### Sun Baked macrumors G5

Joined:
May 19, 2002
#24
At least they stopped trying to teach that pi is equal to 22/7, I hope.

25. ### UKnjb macrumors 6502a

Joined:
May 23, 2005
Location:
London, UK
#25
Um --- don't think so. The defintion that I have grown up with: A number is prime if it is divisible only by itself or 1. If it is divisible by any other number, it is not prime. Which bit is confusing?