I've found this ppt on the internet that it's really nice and easy to understand.

1. PAST SIMPLE
&
PAST
CONTINUOUS

2. Affirmative
Subject Verb
Regular
Irregular
-ed
2nd column
FORMS
Subject was/were Verb-ing
Bart painted
the wall.
Bart wrote on
the wall.
Bart was painting the wall
when Homer arrived.
+
+ +
Past
Simple
Past Continuous

3. NegativeFORMS
Subject verb (infinitivel)+
Past
Simple
didn’t + Maggie didn’t go
to the park
yesterday.
Subject wasn’t/weren’t Verb-ing Maggie wasn’t eating
when Homer phoned.
+ +
Past Continuous

4. QuestionFORMS
Did verb (infinit.)?+
Past
Simple
subject + Did Bart take his
trousers down?
Was/were subject Verb-ing? Was Bar taking his
trousers down when his
mum arrived?
+ +
Past Continuous

5. USES
A completed action in the past
A sequence of past actions
Homer ate the whole cake yesterday.
omer arrived home, he ate the whole cake and later he went
Past Simple

6. USES
Incomplete action in progress in the past
n incomplete action interrupted by another action
Last night at 8 Lisa and Bart were arguing.
Lisa was studying Maths
Past Continuous
ncomplete actions taking place at the same time in th
Bart was skating
Bart arrived home.when
whileLisa was tidying her bedroom.

7. It’s your turn…Past Simple or Continuous?
I_____(write) letters all day yesterday
A cigarette……(cause) the fire last week.
My mother……….(ask) me a lot of questions yesterday.
Their marriage……(end) up in divorce.
What………you……..(do) when I phoned you yesterday?
You…….. (talk) on the phone for hours and hours.
was writing
caused
asked
ended
were you doing
were talking

8. TIME EXPRESSIONSPast Simple
YESTERDAY, I
didn’t go to
school…
LAST WEEK, we didn’t
have lunch together…
TWO DAYS AGO,
Maggie was ill…
IN 2007, Bart
failed all the
subjects…
IN THE 20th
CENTURY, that
didn’t happen…

9. TIME EXPRESSIONSPast Continuous
Grandad was sleeping
yesterday AT 8
o’clock…
I was trying to
fly WHEN it
began to rain…
AS I was working,
the police arrived…
WHILE Bart was
playing, someone stole
his money…
Moe was working
WHILE Homer was
skating…

10. TIME EXPRESSIONSPast Continuous
Grandad was sleeping
yesterday AT 8
o’clock…
I was trying to
fly WHEN it
began to rain…
AS I was working,
the police arrived…
WHILE Bart was
playing, someone stole
his money…
Moe was working
WHILE Homer was
skating…