After passing his secondary school examination, David left the school at the age of 15 years and started getting training under his father. His father, a renowned electrician, had worked for many companies. He everyday started accompanying his father on work and watched him carefully while working. David was a good learner and learnt the techniques of work quickly. Now his father started passing on the tricks of the trade to David. With the passage of time David acquired a high level skill and became a well-known electrician at Indore. Big business-houses started calling him for electrical -wiring .

(a)Name the method of training discussed in the above para.

(b) State any three benefits which David could get on being trained.