Alternative answer for a gapfill

[Martin Jones]

What is the purpose of the alternative answer in a gapfill type question? I was expecting to be able to enter alternative values for all the gaps, but this is not possible.

Scenario: students are entering a pair of coordinates. I would like to accept (x1,y1), (x2,y2) and also (x2,y2), (x1,y1) but not (x1,x2), (y1,y2), etc. What is the best way to achieve this?

I guess a custom marking algorithm is needed. I notice that this contains an error in the alternative answer of a gapfill.

Question: https://numbas.mathcentre.ac.uk/question/1836/find-stationary-points-4/

Many thanks,

Martin

[Martin Jones]

Quick follow-up. I have tried to use adaptive marking to achieve this instead. Please see https://numbas.mathcentre.ac.uk/question/133408/test-gapfill-with-alternative-answers/ for a basic example.

I have tried using the adaptive marking for the gapfill part type, and also on each individual gap. Nothing seems to give the result I want. Any suggestions would be welcome!

Martin

[Christian Lawson-Perfect]

In general, alternative answers are for when you want to try marking the same answer with different part settings. The gap-fill part only really has one setting, "sort student's answers before marking", but you might also use it to try a different custom marking algorithm.

I think what you want to happen is best done with a custom marking algorithm: you could change the `gap_order` note in an alternative to mark the gaps in the order (x2,y2), (x1,y1). If the gaps are defined in the order x1,y1,x2,y2, you'd put this in a custom marking algorithm:

gap_order: [2,3,0,1]

I hope that helps!

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