** Using WeBWorK **

Hi WeBWorK help,

In the set definition file it is possible to set the score for a problem and the maximum number of tries. Is it possible to have the score decrease with the number of attempts made by the student?

Thank you, Tom

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You have to write a custom problem grader. See the examples in setSampleGraders for how to call these in a WeBWorK problem. I'll show you how to write one below. Lets call our new grader decreasing_avg_problem_grader since it will be a variant of avg_problem_grader. If you are going to use this for many problems, you could put your new grader in a file called PGgraders.pl and in that file put the

sub decreasing_avg_problem_grader { ...}

Put the file PGgraders.pl in the courseScripts directory and load it into your problem with loadMacros so your would have code looking like

loadMacros(
"PG.pl",
"PGbasicmacros.pl",
"PGchoicemacros.pl",
"PGanswermacros.pl",
"PGauxiliaryFunctions.pl",
"PGgraders.pl"
);

install_problem_grader(~~&decreasing_avg_problem_grader );

This is the method used by Prof. Zig Fiedorowicz of OSU for his custom graders.

Now how do you write a decreasing grader? Look at the sub avg_problem_grader in .../system/courseScripts/PGanswermacros.pl . You can copy this sub, rename it decreasing_avg_problem_grader and then modify it as follows. Near the end of the subroutine you will find

$problem_state{recorded_score} = $problem_result{score}if $problem_result{score} >$problem_state{recorded_score};

$problem_state{num_of_correct_ans}++ if $total == $count;
$problem_state{num_of_incorrect_ans}++ if $total < $count ;

Note: the $problem_result{score} is a number in the range [0,1] that gets multiplied by the value of the problem (usually 1,2, ... or 10 points) to get the actual student sccore on the problem.

This code replaces the recorded score by the current score if the current score is higher. You also see that you have available the recorded number of correct and incorrect attempts. Just before this code you can modify $problem_result{score}, decreasing it based on the number of attempts or the number of incorrect attempts. E.g.

$problem_result{score} = .5*$problem_result{score} if $problem_state{num_of_incorrect_ans} > 3;

You also have to decide if you want to replace a higher score with a lower one. We do not do this since it discourages students from attempting to get the correct answer.

Finally, you should replace the line

$problem_result{msg} = 'You can earn partial credit on this problem.' if $count > 1;

I would be cautious using decreasing scoring methods. In our experience, we have found that allowing students unlimited attempts without penalty encourges them to work on problems until they get them correct.

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