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

 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.

 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'.