I'd like to write a STACK question as follows:
"Consider the following limit:(etc.)
Does this limit exist? [ans1 - True/false]
If yes, enter its value: [ans2 - algebraic input]"
There would be several (similar) variants of this question, looking almost identical to the student, where in some the limit exists and in some it does not.
I can set up the two answer fields without problems, and check them within the PRT.
However, I run into the following problem: In variants where the limit does exist, and hence ans2 appears in the response tree, Moodle requires that the student enters an answer for ans2 before processing the question. This gives away the answer to ans1 however.
Is there some way to circumvent this? (Except for requiring the student to enter "value 1234" when the limit does not exist - I would like to avoid this.)