This is especially evident in ballet. There are so many details, little nuances and subtle adjustments that are hard to put into words and often are not things that teachers aren't able to discuss in just a typical hour and a half technique class. Look at photos of dancers you admire. See the placement of their fingers, the winging of their foot, their expression! You can learn so many things from just examining photographs of dancers who are creating the shapes and the expression that we all want to achieve.
Here are just a small sampling of ballet photos I adore~
The brilliant Darcy Bussell
The Amazing Alina Cojocaru
The Perfect Paloma Herrera
The Stunning Sylvie Guillem
* I had a hard time finding sources on these, if you know credits please let me know and I will update the post! Thanks!