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Posts Tagged ‘Strange’

An Abacus that works!!!!!!

April 11, 2014 7 comments

Those of you that have read previous posts on Abaci (Here and here) will realise that I have been on the lookout for one that works in our base 10 society. All the simple abaci that are available seemingly anywhere in the country have 10 beads per line, but this doesn’t work. You move zero beads for zero, one for one etc and then when you get to ten you move the nine back and one from the next row across. These ten bead abaci have a bead on each row that will never move!

Today I took my daughter to one of the local parks, as she was playing on the slide I looked across the park and noticed this:

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I was in a state of shock, at first I couldn’t believe my eyes, so I went for a closer look, and sure enough, there it was. An abacus with 9 beads per row. Finally one that makes sense in this society!! well done Leeds City Council.

Amusing, infuriating and worrying exam answers

February 14, 2014 2 comments

Marking exam papers, a strange experience everytime. Full of anticipation, pride, frustration, fury and humour. Some answers are incredibly funny!

The last few weeks have seen my Y8, Y10, Y11, Y12, and Y13 classes all sit internal exams, and as such I have had a lot of papers to mark. While I was marking today one of my Yr12s dropped in and asked what the funniest answer I’d seen were, and there are many. I thought I’d share some of the highlights.

In the recent year 8 test there was a “What’s wrong with this questionnaire?” question, the questionnaire was about pizzas and the second part was: “Tom asked ten of his teachers, explain why this isn’t a good way to collect data”. My favourite answer was:

“Tom shouldn’t ask his teachers because teachers work too hard and as such don’t have time to eat pizza”!

And while we’re in questionnaire questions, why do so many just tick a box?!

We’ve all had the brilliant “explain how you got your answer:” “I guessed”. And a favourite of mine which came up when I was training “can you use your answer to part a to calculate _____” “no” (at least it’s honest!)

The most worrying type of answer is the one that shows there is no common sense being used. Colin Beveridge often tells an anecdote about a student who was adamant the moon was 5cm away as his calculator said so. Today I was marking a paper by a yr11 (who scored a bit overall). There was a question along the lines of “Mary’s goat produces 22.1 litres of milk a day, estimate how many half litre bottles you can fill after 280 days.” The student in question had quite a lot of working out, and came to the final answer of “4”. If you are not open mouthed, look at the question again. See it? More than 20 litres a day, half litre bottles, so more than 40 bottles A DAY, for nearly 300 DAYS! To leave the answer 4 shows that no common sense check has been applied. There were a few instances of this across the class (a top set of very intelligent young people), so I’m going to work on some common sense in our first lesson back.

There was one student who had got slightly mixed up with how many cubic centimetres were in a cubic metre who answered a question about a tank emptying by saying “200000 hours, (haha, I know that can’t be the answer, but I can’t find my mistake)”, which shows that she at least had applied common sense to her thinking.

I once had a pupil draw an actual tree, because she didn’t know what a tree diagram was. A colleague told me his favourite ever was “what are the chances of picking ______ From a box?” which garnered the response “you don’t know till you’ve picked it!”

Then there are these questions I photographed last year, from yr8 tests:

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The most infuriating ones I see at A Level are things like 11^2 = 144, or the ones where a minus sign becomes a plus the line before. Or one that one of my yr13s last year made his specialty, where you copy half the question correctly and then the second half incorrectly, then answer your modified question perfectly, but not get any marks. Or then there the work out a constant correctly, but then write a totally different number in your final equation. These errors are normally met with a “GRRRRR, how many times do I need to tell you? CHECK YOUR ANSWERS!!!!!! “

Categories: #MTBoS, Maths, Teaching Tags: , , ,

Parabolas and televisions

January 11, 2014 1 comment

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Last night, while watching the TV I saw an advert that both intrigued and insensed me.

The advert in question was for a curved TV. It claimed to be curved in order to give you a better viewing experience. My first thought was “Parabolas are coming up with my further maths group, perhaps there’s a lesson in here?”, this was the intrigue, and it was quickly followed by the anger, but more on that later.

Presumably these TVs have been designed to give the viewer the best view, when sat at the focus of the parabola. This is a fantastic real life use of a parabola, and means that this year I will be able to contextualise a lesson that was pretty abstract when I taught it last. I intent to investigate these TVs this week and build them into lessons if possible. I wonder if there is any benefit to positioning them so the wall behind them us the directrix? If there isn’t, I might decide that the folk in my contextualised question want it that way for aesthetic reasons, and/or because they are maths geeks!

The annoyance came while thinking this through. I thought, “how have they calculated that?”, then, “ah, yes, Parabolas, I can see that sitting at the focus could in theory make it all look better,” then, “but what if there is two of you?!” As far as I can tell, the boffins behind this have taken an already anti social activity and made it more so.

As a general rule, I will turn off the TV and put music on if we have guests round. (Obviously, if the purpose if the visit is to watch a rugby match or some other such TV event then it stays on). This is something I have done since the end of the last millennium and started when I was in sixth form. It was prompted by the realisation that TVs killed conversation. This realisation came because a friend of mine lived on her own without a TV and her flat was much more conducive to conversation and good socialising than anyone else’s. It was due to there being no TV to such the life out of the conversation.

So TVs can be antisocial, but people often watch them together with friends, with family etc. But if your TV is parabolic, then the person at the focus benefits, but everyone else loses out!

The logical conclusion to this new “advancement” is that everyone will have their own TV, families lined up watching their own TVs presumably with headphones, to enable them to all watch different stuff. It’s not how I’d want my future!

Of course, I don’t really envisage the world ending up like that (although I suppose I can imagine it). I doubt they’ll take off large scale. Some will fall for the marketing and regret it, most will ignore them and these parabolic telly’s will wind up being forgotten by all. With the possible exception of gamers, who already spent hours locked in isolation only communicating through headsets to the other members of their online world’s.

Pi, and Mary Poppins

January 3, 2014 4 comments

Yesterday we were watching Mary Poppins and we noticed something we hadn’t noticed before. The most surprising thing is probably that is was my partner, not I, that noticed it. What she noticed can be seen here:

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“Why have they got pi on that kite?” she asked.

I’ve been thinking about that question. My first thought was that it may be completely random, although I dismissed that idea fairly quickly. This is a big budget Disney movie, it’s highly unlikely that anything in it is there randomly or by accident. So why is it there? What does it signify?

My next thought was that Mr Banks is acting a little irrationally at that point in the film, and Pi is the most famous of all irrational numbers, perhaps the film makers put it there for this reason? (I did Google this, and not much came up but it does seem this idea had been had before)

Perhaps the film makers just love maths, and wanted to include the picture symbol as a nod to that? Perhaps there was some significance to Pi’s infinite nature?

Do you know the answer? Have you spotted Pi, or any other maths links in other Disney films? In any films for that matter? I’d love to know if you have!

Fractal Christ-maths Trees!

December 2, 2013 Leave a comment

Yesterday was the 1st of December, and as such it was deemed time I our house to put up our Christmas tree. The tree itself is an artificial tree which my parents bought when I was a child sometime in the early 1990s and have since given to me. As such, I have been putting it up for more than 20 years, but this year I noticed something interesting that I hadn’t noticed before.

The tree comes in many parts, and fits together quite easily. The majority of the parts look like this:

 Branch

They are packed away flat, then you spread them out and attach to a pole (the trunk, as it were) and fit together to form a tree that looks like this:

Baretree 

As we were putting it up his year my partner said, “These branches all look like mini trees themselves, don’t they?” This caused a real revelation. The designer of this tree had harnessed the power of fractals to create the most real looking artificial tree I’ve ever known. And this would make sense, given that real Christmas trees do also have a fractal quality about them. Every year I’d been putting up this tree and never realised the mathematical significance it held!

Here is the (almost) finished product:

Finished

And of course, no post about fractals wold be worth it’s salt without the following joke: “What does the B Stand for in Beniot B Mandlebrot?” “Benoit B Mandlebrot, of course!”

Strange Age Restrictions

December 28, 2012 Leave a comment

At Christmas we got many great presents, including this:

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When we opened this we were thrilled, but a few questions sprung to mind. “Why was it the red M and M man on it when it said on the packaging it was a peanut M and M dispenser?” And more puzzling: “why is the age restriction 12+?”

Now I’m in favour of age restrictions and think they are necessary to protect the young, but what is it about an M and M dispenser (complete with M and M’s) that makes it unsuitable for an eleven year old? If anyone knows, I’d love you to tell me as I’m completely baffled!

Categories: Strange Tags: ,

Thanks Asda

December 16, 2012 Leave a comment

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I know that I’m a maths teacher, but surely this is obvious even to those with the most basic of maths skills?

Categories: Maths, Strange Tags: ,
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