On-The-Job Training (OJT)
OJT training, sometimes called direct instruction, is one of the earliest forms of training (observational learning is probably the earliest, see Albert Bandura). It is a one-on-one training located at the job site, where someone who knows how to do a task shows another how to perform it. In antiquity, the kind of work that people did was mainly unskilled or semiskilled work that did not require specialized knowledge. Parents or other community members, who knew how to do a job necessary for survival, passed their knowledge on to the children through direct instruction.
On-the-job training is still widely in use today. In fact, it is probably the most popular method of training because it requires only a person who knows how to do the task, and the tools the person uses to do the task. It may not be the most effective or the most efficient method at times, but it is normally the easiest to arrange and manage. Because the training takes place on the job, it can be highly realistic and no transfer of learning is required. It is often inexpensive because no special equipment is needed other than what is normally used on the job. The other side is that OJT takes the trainer and materials out of production for the duration of the training time. In addition, due to safety or other production factors, it is prohibitive in some environments.