AnswerHints

From WeBWorK_wiki
Revision as of 21:37, 5 March 2010 by Pearson (talk | contribs)
Jump to navigation Jump to search

Answer Hints


This PG code shows how to include two different kinds of answer hints:

  • General answer hints that help students get started on a problem and are made available after a student has submitted an answer at least once (a "Show hints" checkbox appears near the "Submit Answers" button).
  • Specific, customized answer hints that appear in the answer feedback messages box after a student submits a particular answer that activates a pre-programmed hint.


You may also be interested in ErrorMessageCustomization

Problem Techniques Index

PG problem file Explanation
DOCUMENT(); 
loadMacros(
"PGstandard.pl",
"MathObjects.pl",
"answerHints.pl",
);

TEXT(beginproblem());

Initialization: We need to include the macros file MathObjects.pl and answerHints.pl, which only works with MathObjects answer checkers (not old answer checkers). General answer hints only require the standard macros, but specific (customized) answer hints require the answerHints.pl macro.

Context("Numeric");
Context()->variables->are(t=>"Real",u=>"Real");

$f = Formula("2 t");
$answer = Formula("6 u");

Setup: We restrict the variables to t and u

Context()->texStrings;
BEGIN_TEXT
If \( f(t) = $f \), then \( f(3u) \) = \{ ans_rule(10) \} 
END_TEXT
Context()->normalStrings;

Context()->texStrings;
HINT(EV3(<<'END_HINT'));
Substitute \( 3u \) wherever you see \( t \) in the
formula for \( f(t) = $f \).
END_HINT
Context()->normalStrings;

Main Text: We include a general answer hint in the block of text between the commands HINT(EV3(<<'END_HINT')); and END_HINT, which must be on their own lines and at the start of a line. The hint will automatically generate the word HINT: before the block of text that is the hint, so you don't need to add it manually. The modification of the context from texStrings and back to normalStrings ensures that MathObjects (formulas, etc.) will be beautifully typset.

$showPartialCorrectAnswers = 1;

ANS($answer->cmp()
->withPostFilter(AnswerHints( 
  Formula("6 t") => "Are you using the correct variable?",
  Formula("6 u") => "Good work!", 
))
);

Answer Evaluation: To generate specific, customized answer hints for particular answers, we use the AnswerHints postfilter provided by answerHints.pl. The answer hints should be provided by a particular answer, followed by the hash table association operator =>, followed by a string that will show up in the messages portion of the answer preview and feedback box when students submit their answers. You may include as many answer and hint pairs as you like, and even use subroutines in them (see answerHints.pl for more on this).

If the same error message should be given for several different answers, you should make a square bracketed list of those answers. For example, if the variables x, t, and u were all in the context, we could use

ANS($answer->cmp()
->withPostFilter(AnswerHints(
  [Compute("6 t"),Compute("6 x")] => 
  "Are you using the correct variable?",
))
);

If the MathObjects answer evaluator normally generates a message, the default is not to change a message that is already in place. To override a message generated by a MathObjects answer evaluator, you should set replaceMessage=>1 as below.

ANS($answer->cmp()
->withPostFilter(AnswerHints(
  Compute("6 u") => ["Good work!",replaceMessage=>1],
))
);

Problem Techniques Index