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Posts Tagged ‘Vectors’

Infuriatingly impossible exam questions

February 9, 2017 4 comments

Today I was working on some Vectors exam questions with my Y13 mechanics class and I came across this question:

A student had answered it and had gotten part d wrong. What he had done was this:

I have recreated is incorrect working.

Obviously he had found out when the ship was at the lighthouse, instead of 10km away. I explained this to him and started to explain how he should have tackled this when a sudden realisation angered me.

Now for those if you that didn’t work through the question, here is the actual answer:


Can you see what had me infuriated?

This is an impossible answer! If the lighthouse is on the trajectory of the ship and it will hit said lighthouse at t=3 then that would stop the ship! At the very least it would slow it down!!!! In reality it would have to avoid the lighthouse and change trajectory. Meaning the second answer, T=5, would not happen under any circumstances!

My initial thought was: “are they expecting students to spot this and discount the second answer? That’s a bit harsh.”

So I checked the markscheme:


Nope, they are looking for both answers. Argh! I can understand using a real life context in mechanics, I really can. But why not check for this sort of thing!

What do you guys think? Is this infuriating or am I just getting get up over nothing? I’d love to hear your views in the comments or via social media.

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Vectors, Despicable Me and Other Stories

January 25, 2014 6 comments

This week I have been teaching my year 13s about vectors. It had been a while since they had met vectors, so I asked what they remembered about them and one said: “direction and magnitude, they have direction and magnitude. That’s why vector on despicable me chose his name, because he’s committing crime with direction and magnitude!” See this clip.

I had seen the film before, but a few years ago and I had completely forgotten about this character! It is certainly a clip I will share with students in future! (Along with this classic.)

Videos like these are funny and memorable, and can help to embed the knowledge of vectors into the minds of pupils, thus enabling them to recall the knowledge better in an exam. There is plenty of debate around gimmicks and teaching methods. Whether one should be trying to teach or to entertain, but I don’t see why you can’t do both, as long as the entertainment adds to, rather than detracts from, the learning. And videos like this work better than any mnemonic for embedding knowledge and ideas into the teenage memory banks.

The world of entertainment certainly seems to have strong links to maths, the Simpsons and Futurama have for years included maths, which is cool in itself and I think should give plenty of things to use in lessons. Dr Who has plenty of maths, including happy primes and Fermat’s last theorem. The Big Bang Theory is, quite unsurprisingly, the show which keeps on giving, from Thursdays episode which included the mechanics of cow tipping, through topological problems like which cinema to go to to modelling examples, like when Sheldon extrapolated data on Penny’s serial history while on his first date with Amy.

Perhaps more surpringly is the fact that Disney snuck pi into Mary Poppins and there is clearly a maths enthusiast at Universal Pictures who worked on Despicable Me to include the vector character. Even preschool shows are at it! Peppa pig has reference to the quadratic equation and Ben and Holly’s wise old elf uses the golden ratio! Do let me know if you spot any more.

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The mechanics of cow tipping.

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The quadratic formula at Daddy Pig’s office, the discriminant is in yellow.

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