sign up: meaning and explanation
The phrasal verb to sign up for something means to decide to join or participate in something (usually in an official way, e.g. by registering). e.g. I’ve decided to sign up for the gym – it’s time I did some exercise.
We can add an additional object (to sign sb up for sth) if want to describe registering someone else for something. e.g. I’ve signed you up for dancing classes.
We can also use the structure ‘to sign up to do something’ when you want to describe formally agreeing/registering to do something. e.g. I’ve signed up to show new students around the university, so I’m going to be very busy next week.
Have a go at this dictation exercise to hear this phrasal verb being used in context – how much can you understand?