Eleni,
I believe that you need to ask general questions and have certain prompts in mind.
For example:
Question:
What do you find most challenging when completing a writing task?
Prompts:
spelling, punctuation, grammar (e.g. using the right tenses, pronouns…) or syntax (putting words in the correct order)?
Another example is question 14
It may not be necessary to be asked as it may be answered in 13. It can be used as a prompt.