Teaching with Moodle

There is a general issue that you have to be very, very careful if you edit questions after they have been attempted. Some edits are safe, others are not.

For example:

1. If you just change part of the text of a question, for example to correct a typo in one word, then this is fine.
   
2. If you add or remove a bit of a question (for example a choice in a multiple choice question, or a subquestion in a matching question) then that is a disaster.
   
3. (An unrelated example, but useful to know. With multiple choice and short-answer questions, it is safe to change the grade that each answer is worth.)

Because 1) is useful, we don't prevent editing after a question has been attempted. However, the fact we don't have a good way to stop people making the mistake 2) without realising the consequences is bad.

With matching questions, because of the way the student's response is stored in the database, it does not work to change what the right answer is. That is logged as MDL-5560, but there is no easy way to fix that, which is why it has gone unfixed for so long.