Past Progressive / Past Continuous Tense

Past Progressive / Past Continuous Tense
Past progressive à in progress yesterday I, She, He and It à was You, We and They à were It was 10:00. Boris was sitting in class. It was 10:00. We were sitting in class.	The past progressive describes an activity in progress at a particular time in the past. Boris began to sit in class before 10:00 yesterday. At 10:00 yesterday sitting in class was in progress
Past progressive forms : Was/were + -ing	The past progressive uses the past forms of be : was/were + -ing

Using while with the past progressive
(a)    The phone rang while I was sleeping. (b)   While I was sleeping, the phone rang.	While + subject + verb = a time clause . While I was sleeping is a time clause. A while – clause describes an activity that was in progress at the time another activity happened. The verb in a while-clause is often past progressive. (e.g. was sleeping)

While vs When in the past time clauses
(a)    The mouse appeared while I was studying. (b)   While I was studying, the mouse appeared. (c)    When the mouse appeared, I was studying. (d)   I was studying when the mouse appeared.	The verb in a while-clause is often past progressive, as in (a) and (b) The verb in a when-clause is often simple past, as in (c) and (d)

Simple Past vs Past Progressive
(a)    Jane called me yesterday (b)   I talked to Jane for an hour last night (c)    We went to Jack’s house last Friday (d)   What time did you get up this morning?	The simple past describes activities or situation that began and ended at a particular time in the past. (e.g. yesterday, last night etc)
(e)    I was studying when Jane called me yesterday (f)    While I was studying last night, Jane called.	The past progressive describes am activity that was in progress (was happening) at the time another action happened. In (e) and (f) : the studying was in progress when Jane called.
(g)   I opened my umbrella when it began to rain.	If both the when-clause and the main clause in a sentence are simple past, it means that the action in the when-clause happened first, and the action in the main clause happened second. In (g) : first, it began to rain; second I opened my umbrella.
Compare : (h)   When the phone rang, I answered it. (i)     When the phone rang, I was studying.	In (h) : first, the phone rang; second, I answered it. In (i) : first, the studying was in progress; second, the phone rang.