I actually gave her an exercise which would fit your example. First, I gave her a sheet of questions to which she could write relatively short answers:
Are you going on holiday this summer?
Where are you going to go?
Where would you like to go?
Why would you like to go there?
Now give me 3 more reasons why you'd like to go there?!
Who will you go with?
How will you get there?
After she'd answered all the questions, sometimes with only 3 or 4 words, I asked her to write me a piece of around 500 words (for homework) which covered all the answers she had given but of course would require more information in order to reach the word count. She did it. She hated it but she did it!!! But it made her realise the importance of coming up with additional information, either to simply elaborate on a potentially boring answer, or to gain more vocabulary and use more complicated grammar.
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