A vocational G-code curriculum should sequence by what builds on what: vocabulary to recall, then reading, then writing, then machine work, verification throughout.
Grant-funded CNC training programs can cover the whole software layer free: practice apps, open-source machine control, free education licenses, and open docs.
Correctional vocational CNC programs usually run without open internet. Here is how offline G-code learning works, and what makes a tool suitable for that setting.