Being taught by a native speaker will give you the opportunity to learn the language as it is really spoken. An example of this is learning the idioms of English.
There are a huge number of idioms which are used in everyday conversation, as well as writing to a lesser degree.
There is a small selection of these below:
IDIOMS CONNECTED WITH HEALTH:
feeling under the weather - when someone is feeling a little unwell, or a little bit depressed
I need a few days off TO RECHARGE MY BATTERIES - when you feel tired and overworked, and you need a break.
He's fit as a fiddle - said when someone is feeling very well, and in excellent health
I feel off-colour - said when you feel a little bit unwell
OTHER IDIOMS ---
I'm 'thrilled to bits' --- said when you are really excited/pleased about something
I'm on cloud nine - again, this is said when you are very happy about something.
'You shouldn't judge a book by its cover' -----
SOME GRAMMAR ---
anyone, someone - anything, something.
- interesting/ interested. - boring/ bored.