** Using WeBWorK **

I was wondering if there is a way for a field to accept 2 forms of an answer? For example: c/a + c/b or (ca+cb)/ab.

Thank you for any assistance you may be able to provide! -Barbra Bannon

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If you don't want to do that, here is an answer evaluator which might do what you want. It allows the problem writer to specify several answer evaluators. It will test them in turn until it hits one where the student would get some credit and uses that. If they all fail, the student gets no credit.

You can also specify a weight for each answer. For example, a match against one answer might be worth full credit, but if that fails, another match should be worth half credit. One might use this if they were going to ask students to simplify a numerical answer, but give partial credit for an unsimplified answer.

And that's not all. You also can specify a comment to go with each answer. In the scenerio of the last paragraph, a student who gets half credit might appreciate a comment saying that if they go back and simplify the number themselves they can get full credit.

So, the input to this answer evaluator is basically a list of triples (answer evaluator, weight for partial credit, comment). Technically it is not a list but a perl reference to an array. So, you might call it with:

&ANS(pc_evaluator([[std_num_cmp(3), 1, 'Full Credit!'], [std_num_cmp(2),0.5,'Half'], [std_num_cmp(1), 0.1, 'Barely any credit :(']]));

The pc stands for partial credit. The code is below. Comments and suggestions are welcome.

John Jones -------------------------------

sub pc_evaluator {
        my ($evaluator_list) = @_;

        my $ans_evaluator =  sub  {
                my $tried = shift;
                my $ans_hash;
                for($j=0;$j<scalar(@{$evaluator_list}); $j++) {
                        my $old_evaluator = $evaluator_list->[$j][0];
                        my $cmt = $evaluator_list->[$j][2];
                        my $weight = $evaluator_list->[$j][1];

if ( ref($old_evaluator) eq 'AnswerEvaluator' ) { # new style
$ans_hash = $old_evaluator->evaluate($tried);
} elsif (ref($old_evaluator) eq 'CODE' ) { #old style
$ans_hash = &$old_evaluator($tried);
} else {
warn "There is a problem using the answer evaluator";
}

if($ans_hash->{score}>0) {
$ans_hash -> setKeys( 'ans_message' => $cmt);
$ans_hash->{score} *= $weight;
return $ans_hash;
};
};
return $ans_hash;
};

$ans_evaluator;
}

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John

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