# Shocking teacher's error's Watch

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#21

(Original post by

I've had the classic 0.99999...=1 argument. Apparently "0.9999... is an infinitely close approximation of 1 but not exactly 1". And then everyone in the class agreed with the teacher so I was sort of forced to step down. Quite annoying.

**SsEe**)I've had the classic 0.99999...=1 argument. Apparently "0.9999... is an infinitely close approximation of 1 but not exactly 1". And then everyone in the class agreed with the teacher so I was sort of forced to step down. Quite annoying.

I had a Teacher who said that the force of gravity on a parachutist falling at a constant velocity is more than the resistant force. I, like many of you was forced to back down at the threat of a 'detention'. Boo

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#22

About two months ago, I heard my maths teacher say:

"to sum from r=1 to r=n of , you take the sum of the first n integers and turn it upside down."

oops.

"to sum from r=1 to r=n of , you take the sum of the first n integers and turn it upside down."

oops.

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#23

(Original post by

I've had this argument many a time.

It can be mathematically proven and disproven.

So I just tend to abstain from any such argument now.

**EvenStevens**)I've had this argument many a time.

It can be mathematically proven and disproven.

So I just tend to abstain from any such argument now.

Unparseable or potentially dangerous latex formula. Error 4: no dvi output from LaTeX. It is likely that your formula contains syntax errors or worse.

then there is no escaping the conclusion that it is in fact equal to unity.
`\displaystyle 0.99999\!\ldots = \sum_{n=1}^{\infty}{\frac{9}{10^ n}`

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#24

(Original post by

Yeah, it sucks to be the gifted ones...

I had a Teacher who said that the force of gravity on a parachutist falling at a constant velocity is more than the resistant force. I, like many of you was forced to back down at the threat of a 'detention'. Boo

**HarisF1**)Yeah, it sucks to be the gifted ones...

I had a Teacher who said that the force of gravity on a parachutist falling at a constant velocity is more than the resistant force. I, like many of you was forced to back down at the threat of a 'detention'. Boo

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#25

My politics teacher told us that Tony Blair's new job was Middle East convoy... not that that is maths related. But I found it funny nonetheless.

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#31

(Original post by

Convoy =/= Envoy

**HarisF1**)Convoy =/= Envoy

If I've made a mistake whilst mocking someone else's I'll be so ashamed.

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#32

(Original post by

I thought a convoy was something to do with lorries?

If I've made a mistake whilst mocking someone else's I'll be so ashamed.

**vixky!**)I thought a convoy was something to do with lorries?

If I've made a mistake whilst mocking someone else's I'll be so ashamed.

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#34

(Original post by

I recall my maths teacher claiming that 77/6 is divisible by 7 because the numerator is divisible by 7; the class spent the whole lesson arguing with him about it. I'm not actually sure whether he was correct or not, but my understanding is that a is divisible by b if and only if there exists some integer c such that a = bc.

**Dystopia**)I recall my maths teacher claiming that 77/6 is divisible by 7 because the numerator is divisible by 7; the class spent the whole lesson arguing with him about it. I'm not actually sure whether he was correct or not, but my understanding is that a is divisible by b if and only if there exists some integer c such that a = bc.

*numerator*was divisible by 7? i.e. the expression could be rearranged into lowest terms.

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#35

(Original post by

Any disproof is either outright incorrect or built on incorrect assumptions. If we accept

**Zhen Lin**)Any disproof is either outright incorrect or built on incorrect assumptions. If we accept

Unparseable or potentially dangerous latex formula. Error 4: no dvi output from LaTeX. It is likely that your formula contains syntax errors or worse.

then there is no escaping the conclusion that it is in fact equal to unity.
`\displaystyle 0.99999\!\ldots = \sum_{n=1}^{\infty}{\frac{9}{10^ n}`

Unparseable or potentially dangerous latex formula. Error 4: no dvi output from LaTeX. It is likely that your formula contains syntax errors or worse.

.`\displaystyle \sum_{n=1}^{\infty}{\frac{9}{10^ n} = \lim_{R \rightarrow \infty}\sum_{n=1}^{R}\frac{9}{10 ^n}=1`

For the person who claimed it can be disproved... I would be intrigued to know how ....

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#37

My one maths teacher is constantly making some shocking errors... although it doesn't help in her case that she doesn't actually have a maths degree.

Otherwise today I happened to be standing by the door of a class and overheard the pupils arguing with the teacher over ... the teacher kept insisting it was 15 and not 12, and threatened all the pupils with detention if they didn't accept it and stop making a nuisance of themselves.

Otherwise today I happened to be standing by the door of a class and overheard the pupils arguing with the teacher over ... the teacher kept insisting it was 15 and not 12, and threatened all the pupils with detention if they didn't accept it and stop making a nuisance of themselves.

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#38

This I found out that my History teacher didn't know the difference between the noun 'effect' and the verb 'affect'. Quite frustrating he refused to admit that he didn't know the difference even though he spelt it wrong twice!

what was just as bad.. I was the only one who noticed..!

what was just as bad.. I was the only one who noticed..!

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#39

Jeez I'm glad I went to a school that had a good maths department...

The shape of the hanging cable is an interesting one... I believe that if you assume a constant weight/unit length along the length of the cable itself (which is curved) you end up with the catenary, but if you assume a constant weight/length along a straight horizontal line you end up with a parabola. For something like a suspension bridge the weight of the deck, which is the latter, far outweighs the cable. So depending on the context the cable was in the teacher who said it was a parabola may have been pretty much right.

I say "pretty much" because if you're a mathematician you could choose to be extremely awkward, like you have to be to pick up on many of the things mentioned here.

The shape of the hanging cable is an interesting one... I believe that if you assume a constant weight/unit length along the length of the cable itself (which is curved) you end up with the catenary, but if you assume a constant weight/length along a straight horizontal line you end up with a parabola. For something like a suspension bridge the weight of the deck, which is the latter, far outweighs the cable. So depending on the context the cable was in the teacher who said it was a parabola may have been pretty much right.

I say "pretty much" because if you're a mathematician you could choose to be extremely awkward, like you have to be to pick up on many of the things mentioned here.

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#40

(Original post by

Otherwise today I happened to be standing by the door of a class and overheard the pupils arguing with the teacher over ... the teacher kept insisting it was 15 and not 12, and threatened all the pupils with detention if they didn't accept it and stop making a nuisance of themselves.

**.ACS.**)Otherwise today I happened to be standing by the door of a class and overheard the pupils arguing with the teacher over ... the teacher kept insisting it was 15 and not 12, and threatened all the pupils with detention if they didn't accept it and stop making a nuisance of themselves.

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