One Lean principle is Genchi Genbutsu, which means going to see for yourself. This is closely tied to Gemba, which means where the action is. Lean encourages upper management to get into the day-to-day work and get their hands dirty. Many Japanese companies make their upper management work on the floor as part of the training process, including Honda, Nikon, and Toyota.
Taiichi Ohno, the founder of the Toyota Production System, had several famous techniques involving Genchi Genbutsu. One was the three-foot circle. If an engineer had an idea for improving the production line, Ohno would take the engineer to the production floor. He would then draw a circle a few feet in diameter and make the engineer stand there and watch the process for a few hours. After that, if the engineer still thought the idea was a good one, then they would begin planning to implement it.