"Outside or inside?"
Translation:¿Afuera o adentro?
Can afuera be used here? I put "¿afuera o dentro?" and it considered it a typo and corrected it to "a fuera o dentro". Amusingly, even if I am correct, I can't report it with the UI because there's no option for that with "You missed a space."
Edit: Also, if I'm wrong and afuera doesn't work here, it should reject that answer so people can learn.
Helpful discussion about the distinction here: http://www.spanishdict.com/answers/194628/what-is-the-difference-between-afuerafuera-and-adentrodentro
As anomalousjack points out there is a difference in usage between Spain and Latin America though it may be the reverse of what they shared. In Spain the distinction is based on movement, as DaveHarris points out: dentro = inside (static), adentro = "to /towards" the inside (motion); fuera = outside (static), afuera = "to/towards" the outside (motion). And in Latin America no distinction is made it seems. More on the distinction made between LA and Spain here: http://lema.rae.es/dpd/srv/search?key=afuera
Generally speaking, afuera is for movement and fuera for position, as you state. The regional variance consists in that in Spain we are prone to also use fuera for movement (superseding afuera), while in Latin America they might also use afuera for position (superseding fuera).
But even if no distinction is made, one would normally pair afuera with adentro, and fuera with dentro. Jade's sentence sounds odd, but "¿Afuera o adentro?" is, indeed, accepted.
I think might be one of those 70% correct things, but regardless... this link, https://www.realfastspanish.com/vocabulary/afuera-vs-fuera-atras-vs-detras-spanish-adverbs, gives a nice rundown.
The gist is that the a-adverbs like afuera do indicate motion (as others have mentioned here), while fuera indicates the relationship between two objects (Los niños jugaban fuera de la pequeña cabaña). Duo seems to be teaching a third perspective which is that afuera is used to indicate a position without caring about either position viz a viz another object nor motion (Los trabajadores están comiendo afuera).