In the ninth lesson, the students learned about the concept of gender in Italian nouns, focusing on the basic differences between masculine and feminine forms. The lesson emphasized that nouns ending in “O” are usually masculine, while those ending in “A” are generally feminine, although there are exceptions such as nouns ending in “E” that may be either gender. Additionally, the lesson touched on simple transformation rules from masculine to feminine, and noted exceptions including nouns with independent masculine and feminine forms, such as “fratello” for brother and “sorella” for sister.