"Is she a teacher?"
Translation:¿Ella es maestra?
It's explicitly incorrect, according to the RAE. See definition 1.1 here:
I've heard that "estar" conjugations are for something temporary and "ser" are used when something is more or less permanent. I am temporarily happy but i am always an American. Yo esta feliz. Yo soy un americano. Of course the line if temporary vs permanent can be fuzzy. In any event, I tend to think that this idea is really cool and a shortcoming of English. Perhaps it's the incentive behind "e-prime". (And that's a facinating read if you've the time.)
Easy explantion would be Ser is more permanent and refers to WHAT something is. Estar is more temporary and used to talk about HOW something is.
Suggestion for when to use: For Ser...The acronym D.O.C.T.O.R. helps (Date, Occupation, Characteristic, Time, Origin, Relation). For Estar...The acronym P.L.A.C.E. helps (Position, Location, Action, Condition, Emotion).
In Spanish, a question is denoted by punctuation ( ¿Ella es maestra? ) if written, and by the upward lilt of the voice at the end of the sentence when spoken. The word order doesn't change. I don't know whether that is a hard and fast rule, but that is the way Duo teaches it.
A couple issues here. Firstly, you've got to match gender, so it's "un maestro" or "una maestra".
More importantly, in Spanish the article (un/una) isn't used when you're talking about what someone does for a living. It's just a difference in the grammar rules for the two languages. You can find more information about this rule in the other replies on this page.
Same words in the same order, but different punctuation. Instead of: ¿Ella es maestra? you would write Ella es maestra (no question mark). If you were speaking, you would not give your voice the upward lilt on the last word. In Spanish you don't necessarily change the word order like you do in English.
Why can't we have the European Spanish word for teacher included (specifically in the tiles)? My daughter is also learning Spanish at school. Duo used to be arecommended resource but she's not using it much, because it is primarily geared towards South American Spanish