Using idioms is a way to show the examiner your talent with vocabulary and increase your score in the speaking exam.  Using a few of the phrases below in part 3 of the test is a good way to get a score of 7 or higher.

 

Off the top my head…

=without giving it too much thought or without precise knowledge.

 

the first thing that springs to mind is…

= The first thing I can think of

 

the first thing that pops into my head…

= The first thing I can think of

 

I’m sorry I didn’t quite catch that…

=I didn’t quite hear what you’re saying

 

Gosh that’s a tricky question…

=You are asking me a difficult question

 

You can see some more idiomatic expressions here:

https://www.ieltsanswers.com/ielts-vocabulary/idioms.html