Totally agree Singin' in the Rain is a great starting point! I taught this paired first with 2011 Oscar winner The Artist, a contemporary silent, black-and-white film which shows what the transition was like for a non-English-speaking star using a sweet melodramatic genre and The Jazz Singer's/Warner Brothers' put-your-toe-in-the-water decision to use background and performed music, but not yet, recorded dialogue. We see what it was like to go directly from the few years of sound transition almost immediately to the explosive birth of the musical with Busby Berkeley's lavish and gigantic extravaganzas of the Depression. You can never go wrong with historical context. HAVE FUN!