My little Concession Ski School puts together a whole series of training sessions for newbies.
Potential new-hires go to five or six indoor preseason sessions (7:00-9:00pm) lead by the Ski School owner first and then by a variety of Training Directors later on. The first session provides potential instructors with an overview of what ski instruction is all about, what the biggest requirements are that instructors need to meet, and then goes into an introduction to teaching - and especially communicating with students.
After the initial session newbies are introduced to skiing fundamentals as examined via BERP and DIRT along with ideas on how to manage classes, work with problem students and deal with injuries. More recently the owner has been providing (free) PSIA manuals to newbies giving them a head start on more in-depth instructional explorations.
When we finally get snow (late November or early December) we continue with 4 to 6 full days of on-snow training. First we examine their personal capability to actually *ski* (or Ride a Snowboard). A Level 5 or above skier is pretty much needed even to teach beginners. These early-season clinics provide general ski improvement but are also aimed as providing examples on "How to successfully teach skiing to others". Newbies are given documents listing the exact steps to take with beginners and describe how to get students started. Newbies also experience those exact lesson plans on-snow with TD(s) leading their group as though they themselves were the absolute beginners (hard to forget something you've actually done yourself).
In further clinics the newbies are asked to start providing their own mini teaching segments (a few minutes on relevant topics) during the course of the day. Eventually, newbies are asked to pick a topic and demonstrate their own ability to create a lesson plan from scratch and deliver it to a few of their peers (other newbies). This is the Acid Test. Can they now deliver a reasonable lesson and lead others?
All of these sessions are observed by TDs who rate them on key instructor characteristics. By the end of it (late December) newbies know what's expected of them as an instructor, have actually "taught" beginners all the way through Wedge-Christie and have lead/directed small groups on the hill. All the Safety stuff, Area Orientation, Accident Handling and class management gets worked in over the series of clinics.
Pre-Season washouts occur when people demonstrate a lack of interest (no passion for the sport or for teaching), lack of skiing skills (only able to wedge), lack of Safety/Responsibility, lack of attendance (undependable, or obviously skipping out), inability to manage a group, inability to communicate effectively, unwilling to follow directions, etc.
When our season actually starts (in January for 7 or 8 Multi-week classes) everyone meets for a Launch Meeting and newbies get introduced to their supervisors, are given their class cards and are assisted with lesson plans for their first day on snow (generally only a few days away).
For the rest of the season newbies get whatever assistance they need from supervisors, TDs and more-senior instructors. We also provide PSIA Cert Prep clinics all season (after daily lessons end) for Level 1 and 2 though not so much Level 3 any more. There are 'general ski improvement' clinics and some topic-specific teaching clinics when we have the resources and enough interest. Some of us just go out and lead our own ad-hoc clinics if nothing else interesting is happening. We've even done our own spur-of-the-moment dryland get-togethers with video movement analysis.
Right after the end of our teaching season (early March) we provide some day-long clinics to help newbies who want to pursue the Level 1 Cert. We schedule the Level 1 Written Exam in the chalet, and the Level 1 on-snow Exam beginning late morning. Our own (or Local) TDs administer the Exam (a PNW thing) and people get their results by about 4:30pm that day. Most people pass the L1 since we don't (generally) let anyone take it that's not ready to pass it. In the PNW there's no 'Teaching Module' for Level 1 - the ski schools decide that aspect of an instructor's capability.
We also provide after-season support for Level 2 & 3 training as needed if there's interest into April.
My ski school seems to retain most of the new instructors into the next season. Some go off to college, move away or just decide teaching isn't really for them - but most return. If anyone's interested in the Seattle area, we're always looking for competent, capable instructors. Our first start-up meeting isn't until early October, but we're signing people up now.