Simple Past – Past Progressive

Form
Simple Past Past Progressive
irregular verbs: see 2nd column of irregular verbs
I spoke
regular verbs: verb + ed
I worked past form of 'be' + ing form of verb

I was speaking
you were speaking
he / she / it was speaking
we were speaking
they were speaking
Exceptions
Exceptions when adding 'ed' :
 when the final letter is e, only add d.
Example: love - loved
 after a short, stressed vowel, the final consonant is doubled
Example: admit - admitted
 final l is always doubled in British English (not in American English)
Example: travel - travelled
 after a consonant, final y becomes i. (but: not after a vowel)
Example: worry - he worried
but: play - he played Exceptions when adding 'ing' :
 silent e is dropped (but: does not apply for -ee)
Example: come - coming
but: agree - agreeing
 after a short, stressed vowel, the final consonant is doubled
Example: sit - sitting
 final l is always doubled in British English (not in American English)
Example: travel - travelling
 final ie becomes y.
Example: lie - lying

Use
After another or at the same time?
Do you want to express that the actions in the past happened one after another or at the same time?
Simple Past Past Progressive
after another
She came home, switched on the computer and checked her e-mails. at the same time
Simon was playing on the computer while his brother was watchin TV.
New action or already in progress?
If you want to express that a new action happened in the middle of another action, you need both tenses: Simple Past the new action and Past Progressive for the action already in progress.
Simple Past Past Progressive
new action
My mobile rang (when I was sitting in a meeting.) action already in progress
While I was sitting in a meeting, (my mobile suddenly rang.)
Only mentioning or emphasising progress?
Do you just want to mention that an action took place in the past (also used for short actions)? Or do you want to put emphasis on the progress, e.g. that an action was taking place at a certain time?
Simple Past Past Progressive
just mentioning
Colin played football yesterday. emphasising progress
Yesterday at six o'clock, Colin was playing football.
Certain Verbs
The following verbs are usually only used in Simple Past (not in the progressive form).
 state: be, cost, fit, mean, suit
Example: We were on holiday.
 possession: belong, have
Example: Sam had a cat.
 senses: feel, hear, see, smell, taste, touch
Example: He felt the cold.
 feelings: hate, hope, like, love, prefer, regret, want, wish
Example: Jane loved pizza.
 brain work: believe, know, think, understand
Example: I did not understand him.
 introductory clauses for direct speech: answer, ask, reply, say
Example: “I am watching TV,“ he said.
Signal words
Simple Past Past Progressive
 first
 then
 If-Satz Typ II (If I talked, …)  when
 while
 as long as