Quiz

Thank you to Pierre and Joseph for the replies.

Hi Joseph

Thank you for the detail.  I feel that I now understand more about your RegExp plugin, although there is still much to learn.

Here is an example question that requires an ordered response:

List the three primary colours in order of increasing wavelength.

The correct response is "blue, green and red".  It is similar to your flag colours question and can make use of the plugin's regular expression support to allow for different syntax.

It may be desirable to allocate 50% for an answer where the three colours are correctly identified but where the order is wrong.  That can be achieved using the plugin and the regular expression (blue, green and red|green, blue and red|green, red and blue|red, blue and green|red, green and blue).

There are many examples of questions that require a student to list key words in which the order does not matter.  For example, list the three distinct musical instruments used in a conventional string quartet.  This is similar to the primary colours question and, because there are only six permutations, the RegExp short answer is ideal.

An alternative solution is needed when the number of words increases.  For example, name the four bones of the human leg, including the thigh but not including the foot.  The answer is femur, patella, tibia and fibula.

It occurs to me that your Regular Expression Short Answer type is actually what could be called an Ordered List question type (not to be confused with an Ordering question type) that is enhanced by the possibility to include regular expressions in the answers.  As such, it is suited to answers in the form of a series of words or numbers in which the order is important.  I can see that it is ideal for sentence analysis.

It appears that my examples of unordered answers may require an Unordered List question type, which includes regular expression analysis and, probably, additional coding.  This may seem inconsistent with your RegExp Ordered List type.  It seems that there may be a need for the two question types to supplement the existing Short Answer.

There is, however, some common ground. The RegExp plugin appears to offer two possiblities:

• support, through code, for special cases, such as the --.*word.* missing word expression and the provision of hints.
• support through regular expressions.

Both ordered and unordered list questions therefore share these common features:

• both types benefit from regular expressions in the answers.
• the Unordered List type would benefit from additional coding to supplement the use of regular expressions, similar to the RegExp plugin additional --coding that, in conjunction with the Regex .*word.*, can test for a missing word.

Therefore, rather than having two question types, one for unordered and one for ordered answers, it would seem more logical (but also more problematic) to aim towards a full Regular Expression question type with additional code that supports both ordered list, with your extra features, and unordered lists.

In order to test my pure Regex solution to the unordered list problem, based on a 'lookahead' Regex, I have modified two lines of code in the plugin, one in expandregexp.php and one in questiontype.php.  This works. I can, for example, request an unordered list of the eight bones in the wrist.  Unlikely you would wish to do that, but it shows that it can be done with just eight Regex groupings, one for each bone, rather than all the possible (40,000) permutations.

In the first post I suggested the use of the regular expression (?!.*\b(orange|green|black|yellow)\b) as a way to prevent a match if the student answer contains one or more of those wrong words.  I can see that it would be preferable to include coding, as you have for the detection of missing words, to support this feature in the RegExp plugin.  Perhaps something similar to ++coding could be used to trigger the test for unwanted words.

An extension of this idea could be to check the number of words, so that if the correct answer is three key words, as in list the primary colours, and the student enters four words, the code provides a suitable response.

Therefore, my conclusion is that, although, as a temporary solution, I may pursue the pure Regex lookahead approach using a custom version of the RegExp plugin code, that allows the use of all metacharacters, a more satisfactory long-term solution would be the incorporation of code to process both unordered and ordered lists within your RegExp question type.

Regards, Peter