Home > #MTBoS, A Level, Assessment, Commentary > Infuriatingly impossible exam questions

Infuriatingly impossible exam questions

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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  1. February 9, 2017 at 4:50 pm

    It is annoying because if a student did spot that in the exam it would most likely either: a) cause them to lose a mark or b) throw them so that they lost time.

    • February 9, 2017 at 5:38 pm

      Indeed. It could potentially lose them loads of marks via losing time.

  2. February 9, 2017 at 5:17 pm

    I’d have to rate this as annoying. If a student works through without thinking about what the problem models, then they’re calculating without thought and surely we don’t want people to do that. If a student thinks through and spots that the ship will crash then they’re distracted from the test by trying to understand the psychology of the test-writer. Either way seems to be a problem.

    • February 9, 2017 at 5:38 pm

      Aye, I totally agree. No excuse for it.

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