"Corinna has a teacher."
Translation:Corinna magistrum habet.
The case, how the noun functions in the sentence.
magister is nominative singular (the subject, the one doing the action).
The teacher teaches Corinna. -> Magister Corinnam docet.
magistrum is accusative singular (the direct object, the one being directly affected by the action).
Corinna teaches the teacher. -> Corinna magistrum docet.
Just wanting to flag that I am still being marked correct when I make mistakes in the accusative. I put magistra - to go for the female - not magistram and it marked correct with a typo. I am wondering if the algorithm saw it as being close to magistrum perhaps. Nonetheless, I am wrong and hopefully this helps the programme development. Thanks
Yes. magistra, magistrae , f., and magister, magistrī , m., are the gendered words for "teacher."
Please note that all nouns whose genitive singular ( = the 2nd form listed, in the dictionary entry) ends in ae belong to 1st declension; all whose genitive singular ends in ī belong to 2nd declension.