Click the link for a great article from Psychology Today.
Girls who are just told they are smart without reminding them how much practice it takes to gain mastery think that they are innately smart.
When they face a challenge, they internalize it to mean that they don’t have the innate ability to do that skill.
In a nutshell, teachers and parents should be very specific on how they praise their girls. For example, “I can tell how much you have been practicing the piano, you played that song beautifully.”