Use a song with a story to it or a theme that can be discussed. I like to use:
Last Kiss by Pearl Jam - story of a man whose girlfriend died in his arms after a car crash
Working 9 to 5 by Dolly Parton - the music is not to everyone's taste, but there's a great discussion lead in (on working hours, work-life balance etc)
Stan by Eminem - for advanced level students, this is a great story of a fan who is driven to murder and suicide by his obsessions. Discussion topics - obsessions, problems faced by celebrities
Any of these three songs can easily be extended into a 45 minutes lesson. => 5 minutes warmer =>15 min listen to song, review vocab, sing song =>15 minutes discussion topics =>10 minutes students write their own verse
For your homework assignment, you won't need the music, but you'll need the lyrics, which you can download from various sites, like
http://www.seeklyrics.com/
btw, it sounds like your TEFL course is not very well run