The following link shows one way to implemented a timed mini-case assessment which is commonly used in medical education. Each question is timed and the student can't return to an earlier question.
It was implemented as a series of quizes each of which was only available when the previous one was marked and completed. Each quiz contained two questions: the first was a multiple choice question worth 0.01 points and the second was an essay question worth 0 points. The multiple choice question had both alteratives marked as 100% and it allowed Moodle to mark the quiz and thus allow the next quiz to become available. If the student did not pick one of the other they were given 0 for this question but that still counts as a final grade so the next question becomes available.
To mark the minicase the teacher changes the value of the essay question to the real value e.g. 10 points and then the question can be marked in the nomal way. Because the multiple choice question is worth only 0.01 and the number of decimals shown in the activity is 1 it effectively becomes a zero and does not affect the result.
Play the following to see the student view or go to http://emarkingassistant.com/other/educational-adventures/ to see more information and an example.
I hope this is useful to someone ... it has certainly been very useful to us by reducing the cost to deliver and mark minicase exams.
Video showing the student view at
Peter Evans