Last Saturday I was at my house with my girlfriend, cooking dinner.
Yesterday I wasn't home. I was at school; I was in a science class.
Last week, for my birthday, I was at home with my family. And that was really fun. Last night, I was at home doing my homework, and that wasn't so much fun.
On New Year's Eve, I was at a party. It was at my friend's house. It was a lot of fun.
Where was I at this time yesterday? Oh, I was at the gym. I go every morning.