Vivid images always help a child to understand a concept. I often compare performing a musical piece to walking a tightrope. A gymnast on a tightrope carefully watches for his balance and quickly recovers, and a misstep does not really count if a gymnast reaches the end of a rope with a bang. A musician performing a musical piece also balances playing correctly with the right rhythm, articulation, and phrasing. And if he missteps, he needs to quickly recover and keep going to finish the piece - reach the end of a rope and get applause.