Affirmative: (pro)noun + was, were + verb with -ing (we always add -ing at the end of the verbs in this tense)
I saw my English teacher while I was going to school.
Negative: (pro)noun + was, were + not + verb with -ing
He wasn't wearing his glasses.
Interrogative: was, were + (pro)noun + verb with -ing
Was he going to school?
Yes, he was. Or, No he wasn't.