Mentor Trait?
One of the traits you can buy with aspiration points is Mentor. Apparently it lets your sims mentor other sims when they reach level 10 of a career, but my sims have always been able to do that anyway...
Forum Discussion
Trait provides faster skill gain (x2.5 instead of x1.5) while mentoring Activity Table, Basketball, Chess, Homework, Easel, Fishing, Guitar, Mural, Piano, Pipe Organ, Punching Bag, Repair, Robotics, Treadmill, Upgrade, Violin, Wood Working or Writing.
