Achievement-tasks not clearly defined

Greetings,

currently i have a lot of trouble completing the master-mentor-tasks [BH].

The task : reach 3times bronze - for example - means = u have to TAKE PART, not to teach a course ! And that had to happen at 3 ! DIFFERENT ! places (excluding your own property).          That is the way the achievement worked for me, and i was able to get this one.

The task : teach a Sim .... I get this one time, and it was a happy coincidence !       So i drawn the conclusion, that my Sim had to become a Mentor of a npc ...  (... not just teach a Sim !!) . 

... well... and now i am stuck, because i don't know, how to trigger this ...