Dec 07, 2016 - 11:46 AM
Hi Archiewilkie, in general we use "estar" for location, as in "El baño está al lado del elevador". However, we sometimes use "ser" to refer to location because we want to identify a place (building, room, street...) that interests us not for where it is, but for some other reason. So you could use both verbs in that phrase: "Nuestro apartamento es en el quinto piso" or "Nuestro apartamento está en el quinto piso", the program should accept both options.
Since the use of "ser" in this context is quite natural, we used it in some sentences in the program because you will probably hear it in real life (for example, in a taxi you could be asked "¿Es aquí?" referring to a street or a building). That said, this is a bit of a grey area, so I'd recommend using "estar" if you're not sure, because you will never be wrong. Hope this helps!