PAST CONTINUOUS AND PAST CONTINUOUS VS PAST SIMPLE: I was having a shower WHEN the phone rang...

I WAS HAVING A SHOWER...

WHEN THE PHONE RANG

theory:

http://www.aulafacil.com/Ingejerc/Lecciones/Lecc19.htm 

http://www.ego4u.com/en/cram-up/grammar/simpas-paspro 

activities:

http://www.englishexercises.org/makeagame/viewgame.asp?id=734

http://www.aulafacil.com/Ingejerc/Lecciones/Ejerc19.htm

http://www.englishpage.com/verbpage/pastcontinuous.html