"There is a big bag in my house."
Translation:هُناك شَنْطة كَبيرة في بَيْتي.
MountainsMann, in case this helps: The common preposition قي = "in." هُناك = "there. It's a nominal sentence. The MSA word for "bag" is حقيبة while شنطة is common in several dialects, including Egyptian, Palestinian, Jordanian, among others. I'm a beginner, too. Source: Arabic vs. Arabic. A Dialect Sampler, 7.
well knowing how messy is Duolingo's system, I'm not sure this would accepted either. Duolingo is mixing dialect and MSA. The word شنطة is not proper Arabic to start with.
Anyway, your typing here has a typo, it is في rather than فيي (single ي).
But i have to say, such expression is not a proper Arabic.