Hello!
Workers were sent to school to learn special trades was not one of the three phases of industrialization.
Industrialization consists of three distinct phases:
1) Big jobs are divided into smaller, more specialized ones.
2) The specialized workers from phase 1 are put together in large factories forming a production line. The efficiency is greatly increased in this phase.
3) Machinery replaces workers or helps them to perform the production more quickly and better.
As you can see, Workers were sent to school to learn special trades is not a phase of industrialization.
Have a nice day!