"They are playing inside."

Translation: Ils jouent dedans.

[dibidibidis_]

Why not "en dedans"?

[NessaNessaJoy]

when do I use au-dedans, and when just dedans?

[ElFFELTOWER]

I wrote 'jouent' because I knew it meant 'play' but I hovered my mouse over the word 'playing' and I saw that it can also mean 'interpretent' (with an accent on the e). So I wrote 'Ils interpretent dedans' and it marked me incorrectly.

[deactivated user]

Why is "They are playing" not "Ils sont jouant"?

[Ariaflame]

Because they don't use the present participle for that, not the way we use the gerund. http://french.about.com/od/grammar/a/presentparticiple.htm

[deactivated user]

Thanks Ariaflame, for your answer, en for the link as well, very helpful indeed.

[cats00eye]

Why is dehors incorrect?

[lmparis49]

dehors is outside; dedans is inside

[MaCamilitaS]

Its sounds "devant"