While i came into the classcroom today, while i was eating dinner last night, while i was cleaning my teeth last night, while i was doing my homework last night, when i left the house this morning,

While I came into the classroom today, I was singing a song.While I was eating dinner last night, I broke a plate.While I was cleaning my teeth last night, I felt toothache.While I was doing my homework last night, I fell asleep. 

When I left the house this morning, I was thinking about my plans for this evening.