Keep in mind that both the violin and the cello are fit to size and can be started as young as three or four years old. In other words, these two instruments are proportionate to the child’s size (arm length) when they begin and subsequently when your child grows, you are able to trade in this instrument for the new and bigger size to match their growth. The viola is also fit to size but, is generally started several years later than the violin, cello, and piano. Sometimes a child might choose to switch to the viola in his or her teenage years. Other times, a child might decide to start the viola at around nine or ten years old.