"Ese día yo estaba cansado."
Translation:That day I was tired.
I wish Duolingo had a male voice for variety and to show the way those endings change...
Why wouldn't this be estuve? If you're referring to a definite timeframe, shouldn't it be the preterite, not the imperfect?
You're right, it should be preterite. "Estuve cansada/cansado" makes more sense here.
Not necessarily. Using estaba simply describes how he was that day. Using estuve is correct also, but emphasizes that he was tired that day. In this case, neither one is better or worse, they are just different.
"estaba", in Spanish is Imperfect Past Tense; and "estuve", is in Perfect Past Tense. In English, "estuve" = "I was"; and "estaba" = "I used to be". The lesson tries about "The Imperfect".