yea, the older the students get, the harder it is for them to
see you as their mentor or role model, esp if you are pretty
young.
like for me, it was very hard to get the respect from my students
at first. because they were questioning my ability since some of
them are the same age as me and there were a few who were much
older than me.
So i guess in this sense, it is better for me to teach primary
school la 
