Hi!
Here you have exercises to practice the grammar studied in unit 3: Past Simple. After them you will also find exercises to practice the grammar studied in unit 4: Past Continuous and Past Simple / Past Continuous mixed:
http://www.ego4u.com/en/cram-up/grammar/simple-past/exercises?03
http://www.ego4u.com/en/cram-up/grammar/simple-past/exercises?04
http://www.ego4u.com/en/cram-up/grammar/simple-past/exercises?02
http://www.ego4u.com/en/cram-up/grammar/simple-past/exercises?05
http://www.ego4u.com/en/cram-up/grammar/simple-past/exercises?06
And if you want to test how much you know about irregular verbs:
http://www.ego4u.com/en/cram-up/grammar/irregular-verbs
The next one is a funny exercise: first you watch a video and then you have to fill in the blanks with past simple:
http://www.englishexercises.org/makeagame/viewgame.asp?id=2088
Here you have an exercise on PAST CONTINUOUS:
http://www.ego4u.com/en/cram-up/grammar/past-progressive/exercises
The next ones are on Past Simple / Past Continuous:
http://www.ego4u.com/en/cram-up/grammar/simpas-paspro/exercises
http://www.ego4u.com/en/cram-up/grammar/simpas-paspro/exercises?ex07