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Stupid Things Teachers Have Said

Puppycow said:
I think this is stupid, or maybe I'm just ignorant, but a teacher once told me that if you put a cup of hot water in a freezer, it would freeze faster than if you put a cup of cold water in the freezer. I asked if he was sure about it, because it didn't make sense to me. I didn't get an explanation of the physics, but a hostile attitude, like, how dare I question him (he was not a physics teacher). This can't be true, can it? Because hot water would first become cold water before freezing, so cold water would have a head start, right?
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It actually solidifies into clearer ice cubes because the warmth drives out more of the trapped bubbles of gas.
 
Hazel said:
It doesn't?
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Nope. To the best of my understanding, a theory in science jargon is an idea (backed by evidence, otherwise it's a hypothesis) that explains a law. So the law of gravity states that things fall, while the theory of gravity explains how and why.
 
Safe-Keeper said:
Nope. To the best of my understanding, a theory in science jargon is an idea (backed by evidence, otherwise it's a hypothesis) that explains a law. So the law of gravity states that things fall, while the theory of gravity explains how and why.
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Sounds like juggling. I'll think on it a bit. Thanks.
 
Hazel said:
"Biggest mistake I remember is the teacher who said a scientific idea progressed from hypothesis through theory to law. "
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As Safe-Keeper said, a theory and a law are different, and one does not turn into another.

A law is something that is always true- the law of gravity says that two masses attract each other, the law of conservation of energy says that energy cannot be created or destroyed, the second law of thermodynamics says that entropy increases. None of these laws explains -why- these are true, just that they are.

A theory would explain the why of it- germ theory of disease explains why certain diseases occur, the oxygen theory of combustion explains why burning occurs (better than the phlogisten theory, at least), etc.
 
a stupid algorithm makes good

Suppose we want to round 11074996 to the nearest 10000. My sixth grade teacher, whose name I've forgotten, taught us to follow these steps:
  1. First round 11074996 to the nearest 10: 11075000
  2. Then round to the nearest 100: 11075000
  3. Then round to the nearest 1000: 10075000
  4. Then round to the nearest 10000: 10080000 (because, according to her, anything ending in 5000 rounds up)
The correct answer is 10070000.

I protested her algorithm, and was so insistent that she called a meeting of all three 6th grade teachers at our school to consider the matter. Their unanimous opinion: I was wrong.

Her algorithm gets the right answer about 95% of the time. It gets the wrong answer only when the next-to-last step yields a number that ends with 5000, and even then the algorithm gets the right answer about half the time.

I never forgot that, obviously. And so, today, the computer system you're using to view this forum contains several software components that convert decimal scientific notation into binary floating point numbers by implementing an intelligent variation of my sixth grade teacher's stupid algorithm. In certain difficult cases, the algorithm performs a fast computation, related to my 6th grade teacher's incorrect algorithm, to obtain a result that's usually right. The algorithm tests the low-order bits to see whether that fast result could be wrong. If so, then a slower algorithm is used instead. Otherwise we've got the correct result, and we got it quickly.

That algorithm made it feasible for the Java programming languageWP, W3C XML SchemaWP, and the 2008 revision of the IEEE-754WP standard for binary floating point arithmetic to require correct rounding of floating point numbers that appear within a computer program or data.
 
Not sure if this example is stupid or just funny, but I had an Electrical Engineering TA who was . .err . .. English-challenged (I know what you're thinking, but he was Scandinavian).

He particularly had trouble pronouncing longer, technical words, so "resistance" became "restence," "capacitance" became "capstence," and "impedance" became ... "impotence."
 
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My third grade teacher insisted seasonal cycles were due to how close the Earth was to the sun. I told her it had to do with axial tilt, and in fact the Earth was closer to the sun during winter [in the Norther hemisphere]. Not that she believed me.
 
My grade 1 teacher told us about prehistoric life, particularly "dino-sours".
 
dasmiller said:
Not sure if this example is stupid or just funny, but I had an Electrical Engineering TA who was . .err . .. English-challenged (I know what you're thinking, but he was Scandinavian).

He particularly had trouble pronouncing longer, technical words, so "resistance" became "restence," "capacitance" became "capstence," and "impedance" became ... "impotence."
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Similar here, except he was from India. Taught DFynamics.
Got used to verocity being a funyun of itch scared...
 
"Irony is like pornography. You can't explain what it is, but you know it when you see it." - Mr. Morrison, my 8th grade English teacher
 
My headmistress told me that there was no such English word as ere, meaning "before", and argued with me at great length before telling me flatly I was wrong.
Even at the age of ten, I knew she was wrong.
 
Puppycow said:
I think this is stupid, or maybe I'm just ignorant, but a teacher once told me that if you put a cup of hot water in a freezer, it would freeze faster than if you put a cup of cold water in the freezer. I asked if he was sure about it, because it didn't make sense to me. I didn't get an explanation of the physics, but a hostile attitude, like, how dare I question him (he was not a physics teacher). This can't be true, can it? Because hot water would first become cold water before freezing, so cold water would have a head start, right?
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I'm afraid he was right!:)
Congratulations you were right!:(

Sometimes hot water does freeze more quickly than cold, but to muddy the (hot or cold) waters a little, the reverse is also true.
I read the answer in one of the 'Last Word' series (New Scientist) a few years ago and from memory it's all about nucleation points being lessened by the heating, removal of impurities and convection currents being far more active in the heated sample.
Google the Mpemba Effect and see if that gives you a better answer.


Slightly off topic, I'd love a 'portal' on these fora where we can ask our questions and have the resident experts answer them.
 
BillC said:
My headmistress told me that there was no such English word as ere, meaning "before", and argued with me at great length before telling me flatly I was wrong.
Even at the age of ten, I knew she was wrong.
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You just reminded me.
I had an essay marked down because I spelt 'immense' with the double 'm'.:eek: When I pressed him it was the first time I'd heard the expression 'brain-fart' and he marked me back up.




Oh and to the 'VD' poster, it's STI these days, not STD, showing your age old bean.
 
Lolly said:
The hotter it is, the faster it cools, I think.
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Up to a point, but, without looking it up I am pretty sure actual experimentation shows a cup of near boiling w. takes longer than one at 10 degrees C. Ah, heck, I'll check.O733PM E

1). hot faster: http://library.thinkquest.org/C008537/cool/freeze/freeze.html

2). hot faster: http://math.ucr.edu/home/baez/physics/General/hot_water.html

3). cold faster: http://www.physlink.com/education/askexperts/ae7.cfm

4). either, depends (my favorite!) : http://www.straightdope.com/columns/read/422/which-freezes-faster-hot-water-or-cold-water

notice, number four tries two ways, 1 like the first two and one like the third and gets different results AND responds reasonably to his/her results!!:D:D
 
There were so many from a junior high science teacher, but the only one I really remember is an argument I got into with her about how hot you can heat water. Now, I know (and knew then) about issues of atmospheric pressure (more pressure means it takes more heat to turn to steam) and nucleation (if you can't start the bubble then you can super heat the water). No, this was about boiling water without adulterants in a regular ole pot at 1 atmosphere. She contended that you should be able to heat it well above 100C. I explained the physics of it. No dice. Science for her was memorization of facts combined with "common sense" when you don't know the answer (common sense why couldn't you just heat water hotter by adding more heat? It makes perfect sense if you don't understand how/why water turns to steam), not figuring out how things would work based on known principles.

But, for the most part, I got a great education. Just not from her.
 
ShadowSot said:
Couple of more I remembered:

We were holing class on the U.S. Civil War in our American History class in High School.

In the middle of the lecture, the teacher stopped calls, announced that she had these really great shoes she'd recently gotten from her husband, and then passed them around class for the students to smell.

In sixth grade we were supposed to list different forms of matter.
Me, I read ahead. I couldn't remember all of the ones we were supposed to know for the test, so I put down plasma, and got marked wrong.
I contested it, my dad contested it.
She explained that since we hadn't covered it yet, it did not count as a correct answer. I should have memorized the correct answers from the book.

Same lady who made the DNA comment, I think I stopped paying attention in class after that.

What was really sad is she replaced a great science teacher who passed on. The following science teacher who replaced the idiot after I left that school gave me one of his boxes of rocks and fossils he'd collected - I still have it.
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Soo, I suppose Bose-Einstein condensates are right out of it.................:jaw-dropp

(can't test kids on it, it's not in the Sunshine State Standards so it is non-existant and of no importance. I cover it/them anyway.)
 
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