The teacher was explaining an exercise
John was playing basketball
I was playing computer games
We were building a sandcastle in the playground
A mouse was eating cheese in the kitchen
My grandpa was listening to the radio
Judy was eating a hambuger
My brother turned on the TV
They were having dinner
While I was walking to my grandma's house
when a cat entered.
while I was studying in the living room.
when the cat jumped on the table.
when my mother woke up.
I met my best friend on the street.
when I knocked on the door, so he couldn't hear me.
when he broke his knee.
when a bird flew into the classroom.
when it started to rain.
when it fell on the floor.