As a freelance writer, many of my articles have appeared on Gadling.com, Yahoo! Sports, AOL Travel, Paw Nation, Zonder.com, Yahoo! Voices, and Helium.com.
Instructors at all ski resorts in the USA are essentially working for tips. They only get paid when they are actually teaching - which may be 5 hours/day max. After teaching a class of 12 people all day they may have earned $40. In the case of beginners that can be hard physical grueling work.
Most instructors at ski resorts are part-time. Many have a two hour one-way drive just to get to work. $40 does not cover gas money, equipment expenses, professional dues, and mandatory continuing education expenses. Myself and other employees often have to sleep in our cars at night as there is no money for lodging. Part-timers do not receive employee housing benefits or health benefits.
If you received a lesson where you had fun and learned something, reward the instructor for all their efforts. That includes your kids instructor too.