Exercises on line:

PAST SIMPLE AND CONTINUOUS

http://www.englisch-hilfen.de/en/exercises/tenses/simple_past_mix.htm
http://www.autoenglish.org/gr.pastsim.i.htm

http://www.ego4u.com/en/cram-up/grammar/past-progressive/exercises
http://www.englishclub.com/grammar/verb-tenses_past-continuous-quiz.htm