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.
Here's a few to 'whet your appetite ' :
IDIOMS CONNECTED WITH HEALTH:
feeling under the weather - when someone is feeling a little unwell, or a little bit depressed
to recharge your batteries - when you feel tired and overworked, and you need a break. ' I had a day off to recharge my batteries'.
He's fit as a fiddle - said when someone is in excellent health
I feel off-colour - said when you feel a little bit unwell
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.
to 'tear out your hair' - to feel exasperated/ frustrated . 'I couldn't work out how to answer the exam question. I was tearing out my hair'
'looks like something that the cat brought in' - if someone looks very untidy and scruffy.
' to show someone the ropes' - to instruct someone in how to do a job. ' It was his first day in the job, so I showed him the ropes' .
I 'couldn't give a monkeys' - means - 'I don't care'.