Based on the research studies, learning to play piano and music theory can help children with math concepts, reading comprehension and builds self confidence and discipline.
Although there is no specific age which is perfect to start learning piano, there are some physical and intellectual requirements to consider when a child can start:
1- The size of the hand:
Being able to place five fingers comfortably on five adjacent white keys of piano and being able to reasonably have a fine motor-skills( the ability to control finger movements).
2- Knowing the alphabet specifically the first seven letters.
3- Being able to count to at least ten.
4- Being able to focus and paying attention for 30 min.
“a recent study from Concordia University and the Montreal Neurological Institute suggests there are significant benefits to early music lessons. Brain scans of musicians who started training on an instrument before age seven showed stronger connections between motor regions – areas of the brain that help plan and carry out movements such as fingering and coordinating both hands – than those who began lessons later on, despite having the same amount of musical training and experience overall. Early trainers in the study also had better accuracy and precision.”
As conclusion, there are some children who can start at the age of three years old and other children who are able to start at a later age.