Crusher 4
Crusher 4 was the title of a holographic program devised by Doctor Beverly Crusher.

The program featured the recreation of the dance studio where Dr. Crusher had her first dance lesson, including a large mirror and a practice beam. Holographic dance partners were available and music, "Isn't It Romantic?," for example, could be played in the studio.

Dr. Crusher taught Data first how to tap dance and then how to dance properly for the O'Brien wedding with the help of this program. ()

it:Crusher 4
Holographic programs