What is you few of taking fire extinguisher training inhouse.
Currently there are online training available in New Zealand and my opinion is that it needs to be competency based?
I have found that a hybrid approach works best:
Workers undertake the on-line course for the theory and understanding, but still need to physically put it into practice (having attended multiple sessions, there is always someone who can't operate the extinguisher the first time!)
Using this approach also saves trainers time (and your money), as the on-line part can be done well before the practical session.