First step is to familiarize the shooter with the firearm. Muzzle control and finger off the trigger, insert empty magazine. Remove the same. Load magazine with one round. Cock. Fire. Remove the magazine.That's pretty much how I did it when instructing people in using the Glock 17 with "da switch".
Load the magazine with two rounds. Cock. Fire one shot. Fire one shot.
Load the magazine with two rounds. Set on full. Cock. Fire a two shot burst.
Load the magazine with three rounds. Set on full. Cock. Fire one shot. Fire a two shot burst.
Repeat but with more bullets in magazine. Object is to get the user familiar with the recoil of the uzi. Never ever give a full magazine to a novice and tell them go set on full auto and spray.
As several posters in that TFL thread noted, they (or their children) had fired more rounds in full auto by the time they were 8-11 than most adults ever will. There's nothing magic about a buzzgun but, just like with any gun, if certain safety procedures are not adhered to, the results can be traumatic.