When you were learning to ride a bike, did you use training wheels? This is called scaffolding, and it’s a well-known aspect of how humans learn. Scaffolding is breaking skills up into smaller, interlocking chunks that build on each other.
On a bike, training wheels allow you to isolate basic skills - like steering and pedaling - without the added difficulty of balance or fear of falling over. It’s this skill isolation that makes scaffolding so powerful, and your training should be like that, as well.
You probably think your training is scaffolded because it starts with basic skills and moves on to more advanced skills. But let’s take a look at a common set up for welding programs.
Many welding programs put students through increasingly complex types of welds (often called “positions”). And that’s great! But if that’s the extent of the scaffolding, students are going to have a hard time because that structure misses out on the skill isolation that is so important to scaffolding. A better way to scaffold a welding program would be to introduce students to very specific skills, such as how to hold the electrode holder, and then how to stabilize their body, and then how to draw the electrode across the joint, and then…
This might sound strange, but sports trainers have been doing it for decades. Just check out this video on how to shoot a free throw that describes - in minute detail - how to move each part of your body before ever getting into how to actually shoot the basketball: https://youtu.be/nqqw_hYT4QM?t=43
Taking it further, sports trainers often develop drills to practice just one part of one skill. In this ice hockey video, the trainer is working on just one edge of his skate in order to become a better skater: https://www.youtube.com/watch?v=3eZrWGqh42c
You should find ways to scaffold your training in order to isolate the skills your trainees need. Those skills will build on each other and will result in highly competent employees.