"The professor's newspaper is in my house."
Translation:صَحيفة اَلْأُسْتاذ في بَيْتي.
hmm she didn't explain?
Well, Baytak (your house) while Baytakum (you, plural, house). If I want to put it in German to be clear (if you can understand it): Baytak (dein Haus), and Baytakum is (euer Haus).
On a side note, there is also a dual case for two (i.e. your House you two): Baytakumá (it looks long in English but in Arabic it's just one word with a dual suffix).