Which of the following is NOT a part of informal training for equipment repair?

The option identified as correct pertains to the distinction between informal and formal training methods. Informal training encompasses learning experiences that occur outside a structured educational environment. This includes elements like studying manuals, engaging in hands-on practice, and collaborating with experienced technicians, all of which facilitate practical, experiential learning.

In this context, formal classroom training is structured and often involves set curricula, scheduled instruction, and certified educators, distinguishing it from the self-directed and on-the-job learning that characterizes informal training. Therefore, formal classroom training does not fit into the category of informal training, making it the correct answer to the question.